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Dodgerench
Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3110
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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My 2001 Dodge Dakota check engine light came on which was the code P0601. I replaced the

Customer Question

My 2001 Dodge Dakota check engine light came on which was the code P0601. I replaced the PCM. It has thrown the same P0601 on the new PCM. What is your suggestion now?
Submitted: 2 years ago.
Category: Dodge
Expert:  Dodgerench replied 2 years ago.

Dodgerench :

Good morning!

Dodgerench :

The repeating P0601 has nothing to do with you OR your truck... it's an internal checksum error within the PCM itself.

Dodgerench :

Your options are limited to replacing the controller yet again or just living with the CHECK ENGINE lamp being lit forever.

Dodgerench :

Since the code can be set from a checksum error with the software from either the writable or locked side of the controller, you might have success with reflashing the PCM. I tried that recently with a friend's Durango (same controller) and the CE light stayed off for a few days but returned.

Dodgerench :

There are very few choices these days other than to buy a remanufactored PCM since production on the JTEC+ controller stopped years and years ago. Sometimes a simple issue like P0601 slips past quality screening, but I'd expect the next one to be OK. You'll almost certainly have a replacement warranty... right?

Dodgerench :

And once again the PCM needs to be programmed with your VIN and odometer reading. If it has the grey key (with the transponder chip), the new controller has to be introduced to the SKIM system before it will let you go for a ride. Some aftermarket PCM suppliers can do this ahead of time before the controller is shipped... which is much handier than the alternative.

Dodgerench :

If there's any silver lining to the P0601, it's that I've never seen an actual running or reliability problem arise from this code. It's an irritation and it prevents you from knowing when a new problem pops up (constantly on MIL) but other than that... it's business as usual for the PCM.

Customer:

I'm not sure if you saw in my post that I've already replaced the PCM with a re-manufactured one flashed to my vehicle by auto computer exchange. It was the same as your friends Durango it was fine for about 3 or 4 drives and now it is back on.

Dodgerench :

It looks like there might be problems with the site preventing you from entering chat. I'll end the chat to open up conventional Q&A that works much like normal email. Let me know if you have any questions and I'll try to post within the next few minutes (got to head to work soon).

Thanks,

Dodgerench :

Ed

Customer:

I did have an issue with the cruise shutting off after I tapped the brake which is now gone, yet the light is still on

Expert:  Dodgerench replied 2 years ago.
Our chat has ended, but you can still continue to ask me questions here until you are satisfied with your answer. Come back to this page to view our conversation and any other new information.

What happens now?

If you haven’t already done so, please rate your answer above. Or, you can reply to me using the box below.
Customer: replied 2 years ago.
I'm sorry as I was away from my computer for a bit and didn't get back to you quick enough.

I'm not sure if you saw in my post that I've already replaced the PCM with a re-manufactured one flashed to my vehicle by auto computer exchange. It was the same as your friends Durango it was fine for about 3 or 4 drives and now it is back on.

I did have an issue with the cruise shutting off after I tapped the brake which is now gone, yet the light is still on
Expert:  Dodgerench replied 2 years ago.
The cruise shuts off completely? As in turns off and has to be turned back on with the controls?

It sounds like your original PCM did have more than just the P0601 issue. Let's hope you have better luck with the replacement this time. These computer exchange companies usually have pretty liberal exchange policies, so give 'em a ring and they'll get a fresh one on the way.

Knowing what does and doesn't work is great info by the way. You've already established that the speed control issue is gone with the present controller, so I'd expect the problem to remain in remission from here on-out. It's very easy to import problems as well with each controller, so knowing that your only problem at this point is with P0601 is priceless. This PCM also has transmission shift duties, another opportunity for an AW SHUCKS moment...
Customer: replied 2 years ago.
So there is no testing or voltage reading I can perform prior to slapping another PCM in there? I thought I read something about checking voltage readings off the connectors.

The gentleman from Auto Computer Exchange asked me to check the grounds or low battery as this is a cause at times.

The transmission seems to be working fine at this point.
Expert:  Dodgerench replied 2 years ago.
No, there's nothing that the individual vehicle can to to cause the P0601. It's strictly an internal problem, usually described as a checksum error although some model years use wording to imply that it's an internal controller failure. TomAtoes, tomAHtoes.

It's always good to know that your power and ground feeds are in good shape anyway, but rest assured that the solution will come in a box. =/

Gotta run for now, talk shortly!
Ed
Expert:  Dodgerench replied 2 years ago.

Back now. Is there anything else I could help with?

 

Ed

Customer: replied 2 years ago.
I'm concerned and puzzled there is nothing to do other than keep installing PCMs. I would agree with you that is is just a pain and not causing issues with performance. How do you find out what is throwing the check sum off? I've been thinking about selling it and upgrading to a Ram yet seems to be hard to explain the check engine light will never go off and you won't know when there is another issue. It sure seems to me there should be something to read the check sum that is coming up which will lead you to where the issue is located.
Expert:  Dodgerench replied 2 years ago.

In this case, it's out of our hands. Checksum errors happen and it's just yet another unpleasant fact of life with these engine controllers. My feeling is that the error or core problem was already present in the controller you got online but took a few days to act up (like with my buddy's unit after flashing). Nothing external to the controller causes this to happen that I know of and a good replacement unit ends the suffering each time. That's the trick it appears at this point... getting a good replacement part.

 

As for upgrading to a Ram, they use the same engine controller up to about 2003, depending on engine choice. The Next Generation Controller (aptly named NGC) has none of these checksum issue problems which tells me that it's a JTEC thing. Just get an exchange and hope for the best; there isn't anything you or I can do to better the odds of getting a good controller or keeping the new one healthy. In the case of P0601, it is what it is.

Customer: replied 2 years ago.
1 more question for you please. I know on the last unit if I drove the truck at highway speed for approx. 30 to 40 miles the check engine light would go off until I started it again or started in town driving. What would cause it to go off then come back on? I haven't tried this with the new one so don't know if the same symptoms.
Expert:  Dodgerench replied 2 years ago.

You know, I don't know why it would do that and it's the first time I've heard of an instance of P0601- induced MIL illumination going out on it own. They've always just burned the MIL constantly from what I've heard, but I don't always (usually?) get the whole story once a customer talks to the service writers. Maybe that happens more often than expected, but the exact process of checking and qualifying for a P0601 isn't exactly known. They may continuously monitor checksum as you drive or it might recheck only at certain times, keyed to miles driven or key-on minutes elapsed. Dunno.

 

But as Yoda would say... bad it is, exchange it you should. While there's a chance of importing a new problem with the next controller, I doubt that you'll see the same problem a second time in a row and that's just luck of the draw these days with reman controllers unfortunately. We had a run of horrible quality control on our own line of reman JTEC controllers a few years ago, sometimes requiring three attempts to get a good one. And just like you saw, sometimes they roll right out of the box with a P0601 that set immediately which showed there wasn't a whole lot of effort going into the reman/ filter process.

Customer: replied 2 years ago.
I thought that issue was strange when I saw it but thought the same about key time or repeatability and it finally found the correct check sum. I've contacted Auto Computer Exchange to see what they suggest. They are still saying it is a voltage spike or drop. They asked if I ran the vehicle for 15 minutes after I changed it. Is there a burn in time when you install the new one? Would it make a difference if they changed the chip on the original box and re-flashed vs. another re-manufacture? I figured I would get your expert advice vs. their opinion.......Laughing I didn't know if they can read a problem on the bench more than the standard P0601 code. They flashed the replacement to my VIN so it was a plug and play which he stated he would now need to replace the chip to get rid of the bad code.
Thanks
Expert:  Dodgerench replied 2 years ago.

No, I'm sure that your problem lies with the controller and NOT the vehicle. It's a standard concern that poor power or ground feeds can cause some types of problems, but this isn't one of them. No burn-in or learning period is involved, only the internal self-test that happens at some point once the controller is told to wake up.

 

Honestly, I don't know HOW they would even get to the board to replace faulty chips or problems because these units are encased in some sort of synthetic Jello. That's their business I guess..

 

Keep up the fight, Jeff. They owe you a good PCM.

Customer: replied 2 years ago.


Ed,



I'm doing everything I can to get this all worked out. I contacted them and he was going to get with the Tech and see what he has to say. I didn't get a call back yet did see they are sending me another package......lol



I did come up with another issue which might be something I need to address. I had an issue with my passenger door lock squealing and sometimes not unlocking at all. I had to reach inside and force the lock open. The FOB started to unlock all doors at once which I didn’t think was a big deal. I obtained a used one and everything seems to be working fine, except I can't seem to get the FOB to switch from all unlock to just the driver's door first then the others. I also can't seem to get the auto-lock to go off.



I cycled the power on and off 4 times with the 4th staying on then within 30 seconds hit the driver lock to unlock then I should hear a chime. This doesn't work for me, no chime no switch. Is there something with the locking system I should check and could this be an issue with the PCM?

Expert:  Dodgerench replied 2 years ago.
Hi Jeff!
Dang, I'll have to research the door locking sequence tomorrow, but something tells me you're on the right track. Many of the things that we use a scan tool to accomplish... like switching from driver's door unlock with one press to unlock all... can be done by performing some chicken dance like you've described. If the owner's manual says the key cycle thing should work, it SHOULD work. I'll have to look into that a bit more, but can't quite link the PCM problems you're having with the central locking system. Although connected through a common communication bus, they really don't have that much in common.

The squealing of the door lock is a pretty common problem unfortunately. It's the grinding of plastic gears in the door latch assembly that you hear and the only fix is to replace the entire latch assembly. They come as a unit.

I'm actually surprised that the PCM rebuilders are giving you this much trouble and questioning a simple (simple?) 601 code. It's good to hear that they have a replacement on the way though...
Customer: replied 2 years ago.
you are right wasn't sure if it was the chicken dance or hokey pokey.....lol

I figured you might just work it with the scanner but didn't know if the PCM should come programmed with that in it.

Does it matter if I unplug the battery or not before I change the PCM out? Typically we would disconnect power R2 and then hook up power.
Expert:  Dodgerench replied 2 years ago.

No, no need to disconnect power but you can if you like. Just be sure the key is off when you're doing the swap. The only difference you'll see if the battery is disconnected is that you also lost your radio channels. =/

 

Once done, just roll the key ON after replacement... count five... and then you can start the engine. The pause gives the idle motor time to extend/ retract to learn its position and is a major factor in getting a good strong idle right from the start.

 

I still haven't researched your key unlock sequence (rough day)...

Customer: replied 2 years ago.

Ed,


 


I received the 2nd ECM from them. I checked all the grounds I could find and checked the ohms from ground stud to battery and ground strap to ground stud with no major differences. I changed the ECM with battery still connected. Rolled key over paused for a slow 5 count and then started the engine. They suggested I allow the engine to run for 15 minutes for everything to sync which I allowed 21 minutes. I turned the key off and waited 5 minutes. I turned the key back on and you got it..........check engine light was on with the P0601 code. I didn't change the battery yet as it was showing 12.20 volts dc and have had it check with no issues. Is there anything else which I should be checking which would allow this issue to continue? I just can't understand what is going on as I did notice the check engine light wasn't on before I started it.


 


This has me really stumped and not sure what to do regarding try to get another one, get refund and take it to the dealership and take the hit or what. Please let me know what you think as I know it hasn't caused any issues regarding the light but if I try to sell it I'm sure that will be hard to explain. I still can't see to get the key fob single lock, or horn to honk when locked. Could this be an issue I need to check or could be causing the issue?


 


Thank you in advance for your help and I look forward to your advise,


 


Jeff

Expert:  Dodgerench replied 2 years ago.
Hi Jeff!
Am I reading that right? You've gotten TWO replacement controllers and they both code P0601?

With any other code, I'd be crashing around in the cranial attic... trying to imagine what else could be wrong... but in the case of a P0601 there isn't any external cause. It's all internal to the controller. If I happened to have the bad luck of installing a new (reman Mopar) unit and it coded this, I'd replace it without a second thought. If the next one was also coding P0601, I'd replace it again. Eventually you will get one without the internal checksum error and the pain will stop.

You're going to get heat from the PCM suppliers but this is the ONLY solution in the Chrysler Driveability Manual for this code, which amounts to chuck, replace. It's not your fault or the vehicle's fault. It's just a bad part.

I totally dropped the ball on your door lock question! Service information sometimes lags far behind the actual service manual when it comes to features that can be programmed by the customer. It sounded like you already researched that and did their little chicken dance, right?

Ed
Customer: replied 2 years ago.
Ed,

Yes you are correct. I've received 2 controllers from them. I've started the truck with no codes the first time. The check engine light popped up after 4 starts on the first one and after 2 times on the 2nd one.

They acted like it can be caused from bad ground or low battery. This is why I wanted to chat with you prior to calling them tomorrow. I've done everything they have asked other than changing the battery, as I've checked it and had shop check it and it checks out fine. I'll change it if that might be the cause but can't see spending $100 just for the fun of it. I have all 3 ECMs (original and 2 remans) as I wanted to make sure I keep the original in case I need to ask for money back and go to another location for reman facility.

Thank you and please let me know what you think and I will act accordingly,

Jeff
Expert:  Dodgerench replied 2 years ago.
If they won't ship you another controller, it's money-back time. It's not your fault or the vehicle's... they're just bad controllers, period.

Don't buy any lottery tickets tonight. Cripes!

Ed
Customer: replied 2 years ago.
Ed,

I wanted to update you again as I've just got off the phone with them and they are stumped why it is coming up with the code issue. He expressed they HAVE to replace the chip in there just to get rid of the code and it is always bad battery, bad ground or short. I expressed bad box and tell me what to check and I will do it. He goes back to battery since mine is 4 years old but it is showing 12.20 volts dc and when I had it check shop stated it was good so I hate to dish out another $100 just to chase ghosts. I do have an aftermarket trailer light harness attached but it has been on there for years prior to this issue. I did change the ground location to a better location prior to putting in the 2nd ECM to make sure it wasn't that.

This is driving me crazy as every other time I had a PCM or BCM issue on other cars 1st one took care of it. That is why I'm looking for something else to check with might be tripping the check sum difference.

Jeff
Expert:  Dodgerench replied 2 years ago.

Sorry, Jeff... there's nothing more I can tell you. Here is the P0601 diagnostic procedure taken directly from Page 38 of the Drive book:

 

1) NOTE: This DTC indicates an internal PCM problem. If there are no possible causes remaining, view repair*.

 

Repair

 

Replace and program the Powertrain Control Module in

accordance with the Service Information.

 

* This is my asterisk, the bold type was theirs. The last thing stated in any of our diagnostic procedures when

the last thing has already been suggested (in this case nothing because no external

tests are needed or possible), it directs us to "view repair".

 

I'd like to render an opinion, but electronic text is forever these days and that's what lawyers get paid for. Let's just say that I strongly believe you have gotten bad controllers and leave it at that. I'll be glad to opt out of your question if you think a second opinion would help. I'm not upset with you, Jeff. I know you're in a difficult position and it looks like we've come to a dead end at this point.

 

Let me know and I'll opt out to open your question to the JA community.

 

Ed

Customer: replied 2 years ago.


Ed,



I've need to pick you brain a little more please....if you want. Auto Computer Exchange has programmed another ecm and has sent it out. They are still saying they think it is in the battery. I changed out the battery and started it up with no light and no P0601 code. I started it about 6 time and no light. I tried to do the chicken dance with no luck then started the truck and you got it light came on with code. I unplugged the ECM for about 5 minutes and started it back up with again no light. I started it up many times and again no light no code. I then locked the doors, started truck and light came on.



Could you please help me with some info on the locking system? It sure seems like there is some correlation with the lock system and the code. I did install a used lock on the passenger front but they seem to be working fine. What holds the key to the lock configuration? Is there a fuse I might need to change?



I'm sure this out of the ordinary but it just seems to me when I lock or unlock the doors it kicks the code now that the battery is new.



Thanks,



Jeff

Expert:  Dodgerench replied 2 years ago.
Hi Jeff!
Forgive me, but I'm totally out of my element here tonight and can't research much until Monday. But my opinion is still the same.

Try your battery disconnect and just eliminate the power lock factor altogether and the code will still come back. My buddy's 01 Durango at work took a few days for the 601 to come back after I flashed it, but there just isn't any way to get around it that I know of. With a new controller, the code is gone and has been gone now which is consistent with this sort of thing.

If you're onto something with the power door locks, I'll be all ears. Try the disconnect again and avoid touching a door lock for a time period that would be 2x longer than what you've seen the code in remission and we'll see what happens.
Customer: replied 2 years ago.

Hey Ed,


I figured you probably wouldn't be able to give me intel until Monday so no problem. I'm going to mess with it more tomorrow since I now have 3 ECMs.......lol


 


I plan to disconnect and make sure I don't have a code and then start 10 to 15 times and then drive it around for a while. I still can't get the chicken dance to work so I'll leave well enough alone. I'll let you know what happens and see what you think.


 


Thanks again,


Jeff

Expert:  Dodgerench replied 2 years ago.
Sounds good. If you're on to something with a door lock/ P0601 connection, I'd like to be the first to hear the news. I'm not sure what we could do with it... but info is always appreciated.

Wow, 67 degrees at 6:30am. It's gonna be another hot one in Denver!
Customer: replied 2 years ago.

I always say if it were easy everyone would do it.........lol


I wonder could the BCM/CTM be causing the P0601 code? I had the issue with the cruise control and now issue with locking system chicken dance not working.....I wonder if I have a bad BCM/CTM which is sending a false signal to the PCM.


 


I only wish we could have 67 at 6:30.....It was 84 Thursday going to work at 5:30 am I think it hit 107 that day here in Wichita. :-(


 


Let me know what you think regarding the BCM and is there anyway to test it.

Customer: replied 2 years ago.

Ed,


I forgot 1 more thing regarding the BCMs. Do they have to be flashed to the vehicle like the PCM?

Expert:  Dodgerench replied 2 years ago.
There's nothing I know of that a CTM could do to set the 601 code, but it seems every time I figure nothing could possibly surprise me, something DOES.

CTMs don't have to be flashed to the vehicle when replaced except to enable theft systems or program the old key fobs to the new unit. Otherwise they're plug-n-play.

Besides functionality, there isn't much you can do to test a CTM at home. I've seen CTMs that have most features working, but still have a fatal internal error (like the 601) stored when read with the scanner.

Dang, it's easy to forget how easy we have it here at 6000 feet. It cools off about 35 degrees overnight EVERY night and there's almost no humidity during the hot spells of the summer. I promise to not whine any more. =/
Customer: replied 2 years ago.

BCM....CTM I've read that in 01 some had the BCM and some had the CTM...... I pulled the kick panel and have the part number. I also pulled the connector to look for bent pins or loose connectors. It sure seems my issue is tied to the locks. I showed no codes and the light wasn't on when I started the truck probably 20 times and put in gear from time to time with no problems. I pressed the unlock button 1 time and restarted which then the light was on and I now had the P0601 code. I cleared the code and put another PCM in there with no light and no code which stayed that way until I hit the locks again.


 


I thought I had it all figured out and now the light comes on before I hit the locks but I've tapped on the BCM/CTM and unplugged it several times. I'm sure I even have the boxes confused....... :-p


 


Regarding the weather is it already 98 and suppose to be climbing up to 105 by 5pm tonight...........you just have to love the flat plains......lol


 


I'm looking for the schematic for the door locks and some reading to continue with trouble shooting but I think it might have been a combination of several items.


 


Let me know what you think and if I'm headed down the right path.

Customer: replied 2 years ago.
The scanner you are referring to is that like one you can barrow from local part store. Could you walk me through scanning it if that is the scanner I need? Do you access the enable theft system and key fob with the same scanner or is it one that is through the dealer?

It sounds like I might be getting closer yet when I search for the P56045452AK part number on the unit I can't find it in the part stores.
Expert:  Dodgerench replied 2 years ago.
I don't know if you can get into the CTM with most scanners, Jeff. Some modules and systems we have are considered proprietary and won't necessarily be supported by the aftermarket and honestly, I've never tried. It's good to have a "durb" around. :)

We access CTM by going into Body Systems> Body Control Module (it's called that in the DRB for some reason). Since vehicle theft is also living in the same spot, you might be able to get there through that window. Enabling theft and key fobs are both done in the BCM functions.

One of the options you'll always have if the scanner can get into CTM is for trouble codes. See what it's got to say.
Programming key fobs will be another option... just click on it and follow the prompts. The BCMs built after 2000 don't require that all fobs be done at the same time as I recall (unless you're paying someone to do it; that would be a good time to have 'em all rounded up). You can program up to four fobs to a single CTM.

Hmmmmmm.... Take the P off the start of the part number and see what happens. I think the Mopar number would be R6045452AK (it's a reman and for some reason they drop the first number, adding R for remanufactured). Other vendors might do the same thing.

The last two letters (AK) actually represent the software version at time of release, so an AA will be very similar to an AB... all the way to AK if that's the last release. Any of the versions will work and can be flash programmed to the latest version later if needed.
Customer: replied 2 years ago.
Ed,

I found out 3rd time is not a charm in my case with this issue. I'm beginning to believe it is in the CTM as I messed with it for a while to see again if there were any loose pins, connector or something. I plugged it back in and the light and code stayed on and would not go off. I received the 3rd one and light and code 2nd start. I'm thinking about trying to get a used one to see if that would make a change. I'm not finding 1 with my exact part number but thought I would see if you happen to know if I could use a Durango or is there other years I could use. My part number is XXXXX stated P56045452AK and the new number from dealer is(NNN) NNN-NNNNA, for about $375 dollars......wow

I have not tried using the ODB yet to see if I can get to the the CTM but might try that tomorrow. Please let me know if there are any other suggestions. Do you happen to know where I could find a diagram for lock system and info for reading coming out or into pins?

Thanks,

Jeff
Expert:  Dodgerench replied 2 years ago.
Third one? You have yet another PCM setting that stupid code? I gotta be reading this wrong...

There's a certain danger with swapping controllers that have recently lived in another vehicle. The only way I'd say it's OK is if YOUR Dakota has original factory theft (the horn-n-lights thing) and a grey (SKIM) key. These features are taken with the PCM to the new location and will immediately infect the CTM with their information. In the case of vehicle theft, the Dakota would immediately use the anti-theft protocol at each engine start, meaning it would expect to see an RKE or manual lock switch disarm. If you don't have a working key fob... and the truck was never wired with door lock cylinder switches... the truck remains in lockout mode and replacement of both the PCM and CTM at the same time are needed to erase all traces of perceived factory theft.

If YOUR Koda has both systems, you can't be hurt. Swap away as long as the engine and transmission type (including 4x4) are the same. You'd need the controller to work on the same communication bus as yours which narrows the possibilities somewhat yet again. You'd need something built for the 2001 model year and newer. Older controllers use the CCD bus system and yours is a PCI.
Customer: replied 2 years ago.
Yes you are reading correctly Number 3 and since I could get the code to pop after replacing the battery and now it is on all the time I think it is in the CTM.

I want to make sure I've read your info correctly. I have key fob with no transponder in the key. I'm guessing it has anti-theft but not completely sure, so I shouldn't get a used CTM I need a new one. There is a panic button on the key fob but again not for sure about the anti-theft. Is there anyway to tell and am I correct in understanding I should NOT switch it out since I don't have the transponder?

Thanks,
Jeff
Expert:  Dodgerench replied 2 years ago.
I sure wouldn't mess with a used CTM at this point, Jeff. I'm not sure how important it is to avoid cross-contamination between CTMs and vehicles that do and don't have SKIM, but theft is always an issue. PCMs are more sensitive yet, looking for (and learning) systems that come with the donor unit. Better opt for the new one.
Customer: replied 2 years ago.
I wondered about that if I should just get a new one but thought since I have 4 yes 4 PCMs at this time I could take a chance and if the PCM pukes I can just remove and make sure that PCM goes back.........lol I was able to find a new on the internet for $235 and figured I could get it in before I send back the PCMs to see if it clears the original but I will need to have it flashed for the truck........Correct? I know I can learn my FOBs by doing another chicken dance but guessing anti-theft won't work until flashed. Is there any other reason I would have to have it flashed or could I just plug and play?

Thank you again for all your help!!!!
Jeff
Expert:  Dodgerench replied 2 years ago.
I'd just plug it in at this point and get the other programming done later.

Funny story. OK, not so funny.
I've got an 02 Ram 1500 sitting at the shop right now on an approval for a new PCM. P0601. In the next day or two, I'll get the OK to replace and program a new (reman) controller and it will go away. That's the way it's SUPPOSED to work and always has until you showed up with this PCM-eating Dakota!

I'm still skeptical that anything on the vehicle can cause this (you probably figured as much) but I can't disregard your current research.

I replaced three PCMs on the same 2.5 liter 95 Stratus back in the late-90s for a particular problem only to have exactly the same problem emerge again after each and every replacement. I spent untold hours pouring over data and lab scope patterns with multiple digital multimeters connected at the same time, wondering WHAT am I missing ... even learning to blink with opposite eyes to never miss anything... only to find later that all these Mopar controllers were suffering from the same form of trouble that I was trying to fix to begin with.

All these units went through the reman process but it's been my opinion before and since then that none of these controllers were actually rebuilt. They got filtered and sent back out when reasonable doubt suggested that the reason for their original replacement was technician error, ultimately letting the customer do their actual road testing. I kid you not, THREE controllers, SAME exact problem. I'd never suggest that your present PCM supplier would have the same issues, but I thought you might enjoy my little story. Lottery-type odds do exist in the real world sometimes.
Customer: replied 2 years ago.

Ed,


This things is driving me crazy. I was able to locate a CTM with the same part number other than it was AH and mine is AK. I thought for as little as I got it I would try and nothing. It let the doors lock but not unlock. I cleaned the connections and put the old CTM back in with same issue.


 


I've been switching PCMs around with light on most of the time. I put the original PCM with the light on. I went for a drive and the cruise issue came back. That is the one when I set the cruise over 60 once I touch the brake to dis-engage it after it slows down about 10 mph the gauge (speedometer) jumps approx 15 to 20 mph down, the cruise light goes off like you shut it off then it will jump back to normal.


 


I drove it about 3 miles with the cruise on at 70 mph I touched the brake to slow down for the exit, the speedo jumped, cruise light went off and as soon as I turned the check engine light went off all the way home. I turned it off and then re-started it and light came back on, of course.


 


Where is does the signal for the cruise go to and from, regarding like the PCM, CTM.....ect


 


I'll be talking to the supplier again to see what they want to do but seems strange how the light will go off at times.


 


I'm sure you will never see a P0601 code the same way from here out......lol


 


Thanks,


Jeff

Expert:  Dodgerench replied 2 years ago.
I'd say that's odd... but you already know that, Jeff!

Does the speedo ever do that odd jump-thing when you DON'T use the speed control?

I'd associate that little nugget of weirdness to a rear wheel speed sensor, which reports to the ABS system... and the ABS reports this to the PCM who does the math and outputs a vehicle speed signal for the cluster. Rear-wheel antilock (RWAL) systems use a single speed source, which is that sensor in the center of the rear axle. 4WAL systems have left-front and right-front wheel speed signals to sort through as well, which may be why you don't see a complete loss of road speed at times if you happen to have a 4WAL system.

Oh, that 601 I told you I had last week? Somehow the act of installing a new PCM cleared the ABS of its "pinion factor" which made the ABS module really cheesed. It took about a half hour of key-off/ battery disconnect to convince it to let me reprogram the pinion factor but sometimes that happens. Cripes.

If you were suffering from a similar loss of pinion factor in ABS, the ABS (yellow) lamp would flash on and off continuously which I'm sure you'd have noticed by now. VERY irritating.

I'm clueless on your CTM issue at this point. I can easily imagine an UNLOCK BUT NO LOCK situation (from a key-in ignition error) but the other way around is a bit more perplexing. I'd sure like a couple minutes in a room with your Koda and a scan tool...
Customer: replied 2 years ago.

No the weird jump speedo is ONLY with the cruise on over 60, tap the brake, reduse approx 10 mph, jump and cruise light goes off like you turned it off.


 


There is no ABS issues regarding the lamp/light. I think the cruise if probably in the PCM as none of the other remans have the cruise issue, just the dreaded P0601 code off and on. I find it odd that the light comes on at times and then off for a while. It might be 2 starts might be 20 starts.......... :-(


 


I tell you if you were closer I would drive it to you and leave.......I would even block the door to make no one goes in or out..........lol


 


I'm going to mess with it some more tomorrow and call them on Monday........maybe the 4th time is the charm.........hehehe

Expert:  Dodgerench replied 2 years ago.
That's interesting.
I'm wondering if the PCM has a momentary lapse of consciousness when it gives you the BUMP and then turns the cruise off. Does the CE light go out on its own right after one of these events?

When I'm working with someone online and there's a question of whether the PCM is taking a nap or not, my suggestion sometimes is to generate a code of their choice to see if it's still present after an event passes. If the code is gone, chances are good that the controller went nite-nite for some reason.

Just for the heck of it, give that a try. Pull the connector off of any significant sensor on your engine with the key on, check the code to see what it is, then inspire the system to act up by doing the cruise thing. If the new code disappears on its own, it definitely shows a reset is happening for some reason

Loss of power, loss of ground or a short-to-ground of the 5v feed to the major engine sensor group will all do this and allow the engine to recover immediately afterward. Other issues can whack the PCM permanently but it depends how long the failure lasts sometimes.

I've been seeing more and more incidence of short-to-voltage problems on the truck line in this time period and they all happen at the same place. The transmission control 8-way connector and harness on the left side of the trans body, directly above the pan and to the rear of the shift shaft.

It's a roughly round connector that inserts vertically into the case above the pan on the left side. Inspect the wiring in the couple of inches from the connector for signs of bare copper showing or having the wiring all stuck together from heat and exposure to ATF seep.

If the 12v trans relay circuit happens to short to either the sensor ground feed or the trans governor pressure 5v supply, the controller is toast. I only learned of the second possibility within the last few weeks when a Durango rolled in on the hook with a no-response PCM and I found that the 12v output had shorted into the 5v governor pressure transducer feed... both of which come back to the PCM.

After identifying the shorted circuit, I removed the 5v feed from the PCM so I could install a known-good test controller to get it running just to see if there are any other problems. It fired right up I found that the governor pressure sensor was toast, but it ran OK otherwise.

Me being ME, I had to know if the short-to-voltage could actually kill the controller. I mean, it's voltage-to-voltage, so what could it really hurt? So I plugged the C2-31 (violet/white) wire back into the PCM.

Whack.

Remember the P0601 controller I replaced just recently for the guy in Parts? Yeah, the same controller I just got from him after putting his new PCM in just that very morning was the one I smoked on that wiring disaster. That PCM had been running perfectly fine except for the pesky P0601 and I was pretty happy to have a known-good plug-in test unit but it didn't live beyond that moment. It must've fed 12v through the transducer and back to the PCM on the sensor ground feed... hard telling.

I don't see how the trans wiring could be causing your problem, but it's worth a look anyway. If nothing else, it might save you some trouble later if you find something down there. I'll continue to work on a Grand Unification Theory for all the lock/ cruise/ P0601 madness in the meantime.
Customer: replied 2 years ago.
WOW some GREAT information!!!!!
The CE light normally stays on with the cruise thing but this time it went off with in probably a minute of it happening.

? regarding inducing the known fault. Do I leave the sensor disconnected or plug it back in after I see the fault? Which sensor would you suggest?

I will check the transmission control 8-way connector and harness today when I get home. I'm up for checking about anything at this crossroad. I also thought about the lock and it might have been locked but not unlock, but remember that was AFTER I put the salvaged CTM in there. I was upset it didn't fix anything it was all a little fuzzy........lol

Is there any contacts I should check voltage on 1 or all of the 3 connectors common to the PCM to see if I'm seeing an error or spike? I'm pretty sure I'm the next item I'm buying to check it will be a sledge hammer. Cry

I so look forward to the day I say ED that fixed it all is good!!!!! It seems to me the nick in the wire would make sense as if it is short to ground or sending wrong voltage that would explain some of the oddities I'm seeing. I'm planning to re-install 1 of the re-man units as it really seems like there is an issue with original PCM as the cruise thing goes away when the original PCM is not in the truck. That is why I thought maybe the cruise wiring or lock wiring is the issue since those are the items which have popped up since the CE light came on. I also want to make sure the used passenger front locking actuator I put in was from a Durango, that wouldn't cause any issue would it. I had the squealing lock which wouldn't unlock at times so replaced it with a salvaged one.

I thought I would let you know on a side note it was 89 degrees on my way to work at 4:30 am today.......but you wish you could say that.........NOT

Thanks again for sharing and I'm looking forward to a resolution to this......SOON I hope
Expert:  Dodgerench replied 2 years ago.
I'd just unplug and reconnect the TPS, which is on the left (driver's) side of the throttle body. It's one of two 3-wire sensors on the TB and is mounted directly atop the throttle shaft. You'll get a P0123 with an open-circuit disconnect.

I don't think you could create a problem using a Durango door lock unit. Did you say that the lock-but-not-unlock problem began with the CTM you put in?

Cripes, 89 is too hot for the middle of the day, let alone that time of morning! It's cooled off a little here now and I'm going to head to the hills to do a couple days of camping. It's always cooler in the mountains!
Customer: replied 2 years ago.

Ed,

Ok I think I am looking at the right connector and found something I need to ask you about it. You will see in the pictures the connector I think you were talking about yet it is only a 6 plug connector with 5 wires. I had what looked like transmission fluid that dripped out of it (about 10 -12 drops). You can see there is some still in the pin side. I'm guessing that isn't supposed to be there. Does that mean I have something which needs changed and could this be causing my problems? I dabbed out the fluid and dried it the best I could and guessing I should clean with some denatured alcohol.

Please let me know what you think and which way I should head with this find. The wires looked good other than that, no chaffing, cracks or other issues.

I can't seem to attach the pictures. Is there another way to attach them or put them somewhere?

Thanks,

Jeff

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Expert:  Dodgerench replied 2 years ago.
Hi Jeff.
I have to admit that my um... expertise... in transmission related stuff is pretty poor. I think what you're looking at is another connector but I can't identify it. =/

The one I was interested in is definitely eight conductors and is a bit farther back on the trans case and plugs in vertically. I think the one you found is a bit forward of this, so look a bit farther back on the trans case for the one I'm concerned about. It won't cause your 601 code, but is definitely a controller killer if it progresses.

**********************

You definitely got the pictures loaded! And... it's not the one I was talking about even though it's definitely a leaker. I'll see what the device is tomorrow if that's OK, but the connector I was wondering about sits about 6" to the rear and deeper into the trans case. It's behind that big convolute-tube hose that wraps across the top of the trans.
Expert:  Dodgerench replied 2 years ago.
I got a second opinion on your continuing 601 today from someone who knows a bit about the reman controller business.

He suggested that the continuing 601 you're getting is from the ability to change one PCM part number to another. The software being installed at the site is corrupted, so you haven't gotten 4 new controllers with the same problem... you've gotten 4 boxes that have been programmed with the same software glitch that was transferred from a common source. He totally agreed that the 601 isn't caused by anything external to the PCM and that it's an internal checksum error.

Remember that I have none of the capacity for that kind of software change, nor do I know if what he told me was accurate. I'm only suggesting that this is a possibility...

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