How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Doug Your Own Question
Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8568
Experience:  Mitsubishi employed and Factory trained ASE certified technician
21364095
Type Your Mitsubishi Question Here...
Doug is online now
A new question is answered every 9 seconds

I have a 2007 Mitsubishi Galant. If I put a used Pcm in it

Customer Question

I have a 2007 Mitsubishi Galant. If I put a used Pcm in it what else will I have to do besides get the immobilizer re programmed
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Roy replied 1 year ago.

good evening my name is ***** ***** I will assist

you will need to see if the dealer or the shop you have can program the pcm to your vin number. the info from your car needs to be entered into the pcm. then the immobilizer needs to be done

Roy

Customer: replied 1 year ago.
I will have to take the car to the dealer or can I just take the pcm. The thing is my car is about 50 miles or so from the dealership and I don't want to have to pay to get it towed there.
Expert:  Roy replied 1 year ago.

they need the whole car for programming.

did it run with the old pcm??? does it run with the new one????

Roy

Customer: replied 1 year ago.
I filled the car up with gas drove 40 miles and it stopped. It wouldn't start after that. I haven't put a new one in yet. So can I get my pcm flashed or do they need the whole car for that too
Expert:  Roy replied 1 year ago.

as I just stated, they need the whole car.

Roy

Customer: replied 1 year ago.
how much does that usually cost at a dealer
Expert:  Roy replied 1 year ago.

150-175 down here

Roy

Customer: replied 1 year ago.
That's not including labor though right. Is that amount for the dealer to flash my pcm or what
Expert:  Roy replied 1 year ago.

flashing is nothing but labor. there are no parts involved since you are replacing the unit. if you want them to install the unit, it is 1 hour to replace the pcm.

Roy

Customer: replied 1 year ago.
I'm trying not to spend so much money so what would be my best option
Expert:  Roy replied 1 year ago.

I understand. try installing the used one and see if it runs.

Roy

Customer: replied 1 year ago.
I was gonna try that but you were saying I had to take it to the dealership to get it programmed right. I was gonna get one from eBay and put it in to see if it worked
Expert:  Roy replied 1 year ago.

it still may run. it wont be 100% but it would get you there for the service

Roy

Customer: replied 1 year ago.
it will never run 100% with a used pcm? I thought the car would learn the new driving pattern and go from there. So what will I have to go to the dealer for once I put the old one in
Expert:  Roy replied 1 year ago.

no, you do not understand, when you put the used pcm from another car, it may start and run on the program from the other car. then you take it to the dealer and have it programmed to your car. then it will run 100%

try to see f we can save you a tow by seeing if it will run

Roy

Expert:  Doug replied 1 year ago.

I just wanted to interject here before you go buying a PCM thinking it might work....
The used PCM will not run the vehicle in any capacity until it is programmed. The key immobilizer data is stored inside the PCM, when you put a used one in, it will not recognize your keys until it is programmed. This will require a tow to a dealership to accomplish, but is very cheap (usually 1/2 hour minimum labor charge).

Customer: replied 1 year ago.
U saying it will not run until I get the immobilizer programmed to the used pcm I'm putting in.
Expert:  Doug replied 1 year ago.

100% correct, the key immobilizer data is recorded in the PCM, so when you put a used one in it is going to have the key signature from the donor car in it, not your keys... until that is done, the fuel injectors are disabled, there is zero chance it will run.

Customer: replied 1 year ago.
Yea I knew I would have to do that. I just didn't know I still had to take it to the dealer to get it programmed. I thought the computer will learn the emissions and all that.
Expert:  Doug replied 1 year ago.

No, it will adapt all of its emissions adjustments, throttle adaptation, shift logic etc... that will all happen automatically. The key programming to the PCM must be done first though, until that is done it will just crank but not start as the injectors are disabled until it reads a matching key.

Customer: replied 1 year ago.
The other guy said it won't run 100% until I take it to the dealer because it will still be running off the other car program
Expert:  Doug replied 1 year ago.

That was incorrect information unfortunately, which is why I needed to interject; I didn't want you to be under that impression and find yourself stuck still not knowing why it wouldn't run.

Customer: replied 1 year ago.
I did some research and found out that I would have to get the key programmed. I really wanted to get one from eBay or something to see if it will run. I didn't want to spend tons of money at a dealership when I can get a used one to do the same thing.
Expert:  Doug replied 1 year ago.

Very understandable, and yes as you've seen elsewhere the key does require programming if you replace the PCM or the ETACS on this model. When you replace the PCM, it is part of the VIN coding process (you write the VIN, then the scan tool goes straight to key programming).
Unfortunately there isn't any realistic way around this without having them do the programming.... bypass it with donor parts you would be out considerably more money as you would have to swap the PCM, the ETACS, the keys and the lock cylinders in order to have a "match" for the car to start without problems.

Customer: replied 1 year ago.
Hold on I'm getting confused now. So getting the pcm from eBay and getting the key programmed is a bad idea. It sounds like u are saying I have to do more than that if I go that route
Expert:  Doug replied 1 year ago.

No not at all, I apologize that was a little hard to read.

If you get a used PCM from ebay, you will need to tow it to the dealership and have it programmed (VIN and key programming, one step process).

I was saying that there isn't any affordable way to get around doing that, as the only way to avoid having the programming done would be to get basically the entire immobilizer system (PCM, ETACS, keys, locks). If you went that route you would not require any programming at all (though the VIN would read incorrectly on a scan tool, it would "think" that it matched and wouldn't pose a problem). This would be considerably more work than just getting a used PCM and towing it to a dealer for programming though.

Customer: replied 1 year ago.
the programming u are talking about is just the key programming right? I was thinking it was something else when u said programming. So u are saying the VIN and key programming is one in the same.
Expert:  Doug replied 1 year ago.

Pretty much yes. It is a single process that writes the VIN and programs the key in one process.

This is not like Chrysler PCMs where there is actual engine control data being written etc, Mitsubishi PCMs aren't like that. They just need the VIN write and key program which is a one step process on the scan tool, takes only a few minutes etc.

Customer: replied 1 year ago.
Ok everything is clear to me now. Be honest do u suggest getting a used pcm
Expert:  Doug replied 1 year ago.

Honestly.... I've been working for Mitsubishi for nearly ten years, and I can count on my fingers how many of these 2004-2011 Galants I've had to replace a PCM on. So while it is a pretty safe bet you'll get a good one, it is also a somewhat safe bet yours might not be bad.
What is the nature of the failure?

Customer: replied 1 year ago.
Well I filled it up with gas drove it 40 miles it stalled then shut off. It start but won't crank. Replaced the timing belt cam and crank sensor still nothing. Then yesterday I notice one of my coils melted into the valve cover. Put the scan tool on it but it wouldn't connect to it
Expert:  Doug replied 1 year ago.

Gotcha.

I assume the timing belt had not jumped or anything right?

With regard to the coil melting... these coils do fail like this, however it is possible the PCM caused the failure. It is rare, but does happen.

The engine light doesn't work currently I take it right?

Have you verified all of the fuses, including the ones inside the dash (the coil fuse surely blew if the coil melted, that one is in the dash)

Customer: replied 1 year ago.
The check engine light came on and I checked all the fuses inside the car but not all the fuses under the hood yet. The coils were a lil cheap on there though
Customer: replied 1 year ago.
I'm not being charged for each question am I
Expert:  Doug replied 1 year ago.

Nope, one charge is all.

If you mean the coils were aftermarket ones, then that is not too uncommon for them to fail anyway.
So does the engine light work currently?

And the timing belt was not jumped/broken when you changed it?

Customer: replied 1 year ago.
Not it was not just changed it. Yes the engine light works it came on when the car started running bad
Expert:  Doug replied 1 year ago.

But does the light come on now, even if just briefly? This is important as it is an indication of if the PCM is doing its self test at key-on.

Customer: replied 1 year ago.
Yea it comes on
Expert:  Doug replied 1 year ago.

Great, that is half the battle in itself.

Are you able to check for spark while cranking? What about fuel injector pulse?

Customer: replied 1 year ago.
It's getting spark as well. Fuel pump is working as well. I put a scan tool on it but it wouldn't connect to the computer to give me any codes
Expert:  Doug replied 1 year ago.

I wouldn't concern yourself too much with the scan tool issue... these cars are very finicky about who they talk to, and many auto-parts store scan tools can't talk to them at all.

Knowing the light is coming on, we know the PCM is waking up. Knowing there is spark and fuel pump operation, we know the crank sensor is working in at least some capacity.
For a component failure, this makes a pretty strong case for a cam sensor; otherwise I would also be a little suspicious of the fuel itself.
When you replaced the cam sensor, was it a factory one or aftermarket (purchased anywhere other than a dealership, regardless of packaging)? This is relevant as this vehicle has an issue with aftermarket cam sensors... crank ones aren;t too bad, but the cam ones are extremely rare to work.

Customer: replied 1 year ago.
They both came from auto zone
Expert:  Doug replied 1 year ago.

Yeah I'd put the original cam sensor in first and foremost then. Its sad, but those cam sensors are literally about 10:1 odds of working... they are a huge source of headaches (and tow ins to my shop, conveniently).

Get the original cam sensor in there and see if it sounds at all different when cranking. Then take some starting fluid/ether and give it a few shots into the intake duct and see if the engine catches briefly.

Customer: replied 1 year ago.
Any other suggestions
Customer: replied 1 year ago.
What if it catches briefly then what
Expert:  Doug replied 1 year ago.

If it catches briefly, then you would be confirming your compression and spark timing are all OK.... leaving you with just fuel control, either you did have a bad cam sensor and just need to get a good one, or you have a fuel source issue (contaminated fuel). The latter would not be too unlikely considering the close timing between the fill up and the problem occurring.

If it does not run on starting fluid briefly, then we might consider a possible PCM issue, but given how many indicators you have that it isn't the problem, I would be surprised. At that point we would want to check the injector pulse on an oscilloscope to see if it is controlling the injectors properly; same for the coils to make sure they are firing in sequence; then compare cam and crank wave forms to make sure they are normal.
If there is a problem with the PCM, it would pop up on one of those tests... though again I'd nearly bet the house against it with you having a working engine light, spark while cranking and fuel pump operation. Those are very unlikely to work with a bad PCM, as these PCMs usually are all or nothing... if it is bad, you have no light, no spark, etc.

Customer: replied 1 year ago.
if the pcm was bad the engine light wouldn't come on at all?
Customer: replied 1 year ago.
Well all the lights come on inside the car
Expert:  Doug replied 1 year ago.

I'd say about 80% of the time, yes.
When we see the PCMs fail you usually have complete failure, light doesn't even come on, or you have individual driver failures... where it runs, but you lose one ignition driver, or one injector driver etc.
I can't think of a single instance of total lack of running and still having the PCM power up.

Customer: replied 1 year ago.
Now u make we want to go check everything all over again and make sure it's doing everything u suggested. Can u please give me a list of everything to check if that's not asking too much
Expert:  Doug replied 1 year ago.

Not a problem... I'd definitely be rechecking everything, PCMs are just too rare to fail on these.
If you have an oscilloscope then checking the wave form on the cam and crank sensors would be ideal. Without it....

Verify spark on all four coils while cranking.

Use a noid light or test light on each injector and confirm injector pulse on each injector while cranking.
If you have both.... try alternative fuel source, as your only real expectations if you have fuel delivery and spark are going to be compression (not likely if the timing belt didn't break and is installed right) and fuel quality (pressure as well as contamination).
If you don't have spark and pulse on all cylinders, then check both the cam and crank sensors to verify the 5V wire with the key on is present, if it is then back probe the 5V wire and manually rotate the engine to make sure you are getting on/off signal from both sensors. This is not as effective as an oscilloscope inspection, but does giv eyou at least an idea if the signal is missing entirely of course.

Expert:  Doug replied 1 year ago.

If you have spark but no injector pulse on any injector... then there is possibly an immobilizer issue or cam sensor issue. The former would require a trip to the dealer of course.
If you have spark but only initial injector pulse then nothing, expect the cam sensor.
If you have spark only on certain coils and/or injector pulse only on certain injectors, expect a possible PCM issue provided the timing belt is timed right (it will drop partial control if it is out of time).
And if you are missing the 5V signal to either cam or crank sensor, expect a wiring or PCM issue.

Customer: replied 1 year ago.
what would cause the pcm to go out
Expert:  Doug replied 1 year ago.

Not much.... for a complete failure there is usually someone having a hand at it.... doing some "custom" wiring and causing problems, or sticking a test light in places they don't know what they are probing, shorting out the PCM.

For the typical failures we see, usually cheap ignition coils will internally short the 12V supply voltage to the 3V trigger wire and blow out the driver inside the PCM.

Customer: replied 1 year ago.
I was thinking when my coil melted it made the pcm go out. The coils are very cheap on my car I can't lie
Expert:  Doug replied 1 year ago.

Its definitely playing with fire using aftermarket coils on the Galant/Endeavor of this era... they (among most electronics for this generation) are very problematic.
However it would be incredibly unlikely if not impossible for that alone to cause a complete PCM failure. It would only blow out the 3V driver, resulting in the affected cylinders coil no longer firing.

Customer: replied 1 year ago.
I need to check everything u suggested first before I get the pcm
Expert:  Doug replied 1 year ago.

Absolutely. The PCM should normally be your last option anyway, but this is even more true on Mitsubishis and this model. You have way to many things pointing toward something more minor (bad tank of gas, new-but-bad cam or crank sensor,, etc).

Related Mitsubishi Questions