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Jon
Jon, ASE Certified Technician
Category: Dodge
Satisfied Customers: 310
Experience:  Master Chrysler/Jeep/Dodge Tech
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I am working on a 2002 Dodge Ram and need to ask a few

Customer Question

I am working on a 2002 Dodge Ram and need to ask a few questions about the vehicle's electrical system. For example, the single CAN system. I am a fuel injection system technician. If possible is there a Dodge technician I could speak with in Spanish?
Submitted: 1 year ago.
Category: Dodge
Customer: replied 1 year ago.
The computer, dashboard, fuse box, radio, climate control and light dimmer were stolen from vehicle as well as all of the wire connectors. I put the parts from other vehicles and the car would not start. After a few months, I was able to recover what was stolen and installed everything back into its original place, but the car still will not start. My scanner reads all of the modules except the PCM, and says lost communication with the PCM. I have checked all of the wiring that was cut with diagrams. It is like the PCM is blocked, is that possible? I have tried with 2 more used computers of the same model and year, and still no communication with the PCM. The skeem light turns on in the dash, when I turn the key on the light goes off for 3 seconds and then comes on (it doesn't blink) it just stays lit up. The vehicles original modules are installed because the cars vin number is ***** on them. What can I do? Is there a way to make sure that the computer is connected correctly? (I have a machine to check car computers outside of the vehicle.) By the way the car is a 2002 Dodge Ram, 4.7l, AT, 4X4, crew cab, assembled in Mexico. The VIN is 3D7HU18N82G176358.
Expert:  Jon replied 1 year ago.

Hi, can you tell me if your Ram's PCM has 3 or 4 connectors?

Customer: replied 1 year ago.
3 connectors , white , gray and black
Expert:  Jon replied 1 year ago.

Ok, I'll get back to youwithin the hour. I'm at lunch.

Customer: replied 1 year ago.
Ok , remember I pay for a fast answer
Expert:  Jon replied 1 year ago.

Ok, C1 black pin 2 should be hot in run, pin 22 should be hot at all times, pins 31 and 32 should have a good ground. Check those and let me know what you have.

Customer: replied 1 year ago.
It is ok , four is good
Customer: replied 1 year ago.
Look when I turn the ignition switch on the volt for the sensor is lest to 5vts, for example the ckp or cmp or tps , like 3.5volts, I change the computer and do the same ,
Expert:  Jon replied 1 year ago.

C3 gray, pin 30 is the pci bus. Ohm that to pin 2 of the data link. It's a light blue and purple wire. If that checks out good and all of your powers and grounds are good at the pcm, the pcm is bad if you can't communicate with it. Your data bus is nota can bus, just a single wire pci bus.

Customer: replied 1 year ago.
The ohms continuity of pin 30 to data link connector is good. I have changed the computer with two other computers as well as the original, so I don't think that it is the computer because 3 different computers can't all be damaged at the same time...Do you the immobilizer is blocking communication? And in the computer what does the shut down relay do?
Customer: replied 1 year ago.
If this is outside your field of expertise, then connect me with a technician who has experience with reprogramming Dodge car computers and skeem modules. I need help ASAP. Thank you.
Expert:  Jon replied 1 year ago.
It's not, what more help can I give you? Did you ohm out the pci bus to the data link? If all powers and grounds are present at the pcm and the pci bus wire is good between the data link and pcm and you can't communicate with it, the pcm is bad. There are a few exceptions with that statement if a crank position sensor is shorted but I've never seen that on an 02 ram.
Customer: replied 1 year ago.
Do you know if the PCI bus signal is important to star de PCm, not the data link connector , the can signal , one cable , do you think the skeem module give a signal to open de volt to the pcm? , I given one order to block the pcm? ,
Customer: replied 1 year ago.
I see one more thing , the abs module given one code said , vin number not match,
Expert:  Jon replied 1 year ago.
This truck does not have a can bus. It's a single wire pci bus. You said you can communicate with everything except the pcm so that rules out the pci bus being shorted or open with the exception of an open to the pcm. Yes it does need an ok to start message from the skim module to start the engine but that has nothing to do with you not being able to communicate with the pcm with your scanner. If you can't communicate with the pcm, either it's missing a power or ground, or that pci bus is not connected to the pcm, or the pcm is bad. That's the general rule for a non responsive module. If all the powers and grounds are present and the bus wires are good and it doesn't communicate, the module is bad. There are some exceptions I've seen on jeeps to that rule where a crank sensor can short out the pcm and prevent communication.
Customer: replied 1 year ago.
Ok , please send me a diagram of the computer for the 2002 Dodge Ram to compare with my diagram I have from AllData to see if they are the same. And, if I disconnect the CKP sensor, can I check to see if there isn't a short? Do you know if this make of Dodge should turn on for at least 3 seconds and turn off if the immobilizer is activated? Thank you for your help.
Expert:  Jon replied 1 year ago.

One question I missed that you asked about the ASD relay, that sends power to the injectors and ignition coils and a few other things, then the pcm grounds the other side of them to turn them off and on.

Expert:  Jon replied 1 year ago.

I can send you a diagram in the morning but I'm not sure what you're asking me right now. If the skim isn't recognizing the key as valid, yes it will start and stall after a few seconds. Considering you swapped modules around, you might need to run a pcm replaced function. There's a secret key code (not the skim) that has to be transferred between the pcm and skim when you run that function.

Customer: replied 1 year ago.
I think that may be close to what the problem is, because remember that the fuse box was stolen and I reconnected it. So in the diagram, there are some cables that are the same color, maybe they are connected wrong. Is there any way to directly connect the ASD relay ? Or the fuse box module that controls that relay maybe damaged and so the PCM doesn't turn on? Please give me an idea, thanks. Because I have checked all of the connectors to the PCM but I don't know how to check the fuse box signals.
Customer: replied 1 year ago.
When I turn the key to the on position, the skim red light turns off for 2-3 seconds, then it turns back on and stays on. Now all of the vehicle's original modules are installed: the fuse box with the module, the PCM and the instrument panel. Do you think the skim module could have been blocked because I put other modules (fuse box with the module, PCM and instrument panel)? I'm asking you this because a mechanic at a Dodge dealership that I went to talk to told me that the modules are blocked for the above reason and that I have to install all 3 modules brand new and reprogram. I don't believe that. Explain to me what you think please.
Expert:  Jon replied 1 year ago.

I would look in your scan tool for a pcm replaced function in the skim module and try to run that. If your scanner has that, let me know and I'll get you the skim code.

Customer: replied 1 year ago.
Hello, I have a Otc touch , launch gds, this do everything , only Is no possible read de pin code , can you help me with this ? By vin 3D7HU18N82G176358 ,
Customer: replied 1 year ago.
Hello, what up
Expert:  Jon replied 1 year ago.

4403 is the skim code for that vin

Customer: replied 1 year ago.
Thank you so much! I am going to try it out this afternoon and I will let you know.
Expert:  Jon replied 1 year ago.

No problem, let me know.

Customer: replied 1 year ago.
I am open the system , but doesn't open the PCM communication , soy I thing you rite , when have to check the computers voltage and grounds , please sen to me the diagram (PCM) connectors to check and please explain to me about a shout Dow control relay ,may be something in this , because I change 3 computers and all of this do de same , so I thing is something wrong , not the pcms
Expert:  Jon replied 1 year ago.

The ASD relay just supplies power to the fuel injectors and coils and a few other things. It has nothing to do with communication. If you can't communicate with the PCM, it has to be missing a power, ground, or the pci bus is open. With all those present and if you're sure the pcm is good, it has to communicate. I would go over those pins at the pcm again and ohm the pci bus from the data link again. If you can't communicate with it,it has to be one of those I just mentioned.

Customer: replied 1 year ago.
Ok , I am check again the grounds and power , thank you
Expert:  Jon replied 1 year ago.

Ok. Let me know what you find.

Expert:  Jon replied 1 year ago.

I'll have to look this up tomorrow what it should be but measure the voltage on the pci bus pin at the pcm if you don't find any missing powers or grounds.

Customer: replied 1 year ago.
Can you help me please? Do you know what the procedure is when you change a used computer for this car that I have this problem with? Is it similar to the procedure for Chevrolet where you turn the switch on for 15 minutes 3 times and then the computer matches to the car? I don't know what the steps are for a Dodge, do you? I have heard that leaving the switch on for an hour, but that's all. If you can explain this to me, thank you.
Expert:  Jon replied 1 year ago.

You're going to go into the WCM and run the PCM replaced function. Follow the directions on the screen and it should go through.

Customer: replied 1 year ago.
What tool is WCM , I don't know , help me please
Expert:  Jon replied 1 year ago.

The WCM IS a module on the truck, that's the module you go into to program keys. I don't know if the OTC Scanner can get into it or not but if it can, the PCM replaced function should be under miscellaneous functions.

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