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truck will only run with c3 unplugged on PCM!!!!

Dooner
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Dooner

Dooner

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Posted

Guys i am in need of some insight. I have a 1999 24v cummins.  This truck has been a headache to say the least but i am at a standing point. This is what has been replaced in the last 6 months and has been at 4 different shops including a chysler dealer. They have all given up but i am not ready too. 

 

The truck will only run when the c3 plug on the PCM is unplugged. This is the plug nearest the passenger side fender. This is what has been replaced

 

IP

Liftpump- stock replacement

PCM- has been flashed to match VIN at chyrsler dealer

engine harness has been replaced with one out of a running truck with same year and details( 4x4, auto ) 

ECM has also been replaced. 

Injectors were replaced with 100+hp from superior turbo and injection 

PCM harnes was replaced with one out of a running truck with same year and details

 

I have come up with no codes as i have a CTS2 insight and it says there are none as the other shops have been saying all along. 

 

Truck runs great and starts right up when c3 plug is unplugged. You can drive it around and it seems to run good but the voltage, gas gauge, temp, speedo, oil pressure does not read.It also will only shift to second gear and nothing more as im sure its because the c3 is unplugged. I have checked when the c3 plug is in for codes and it comes up with nothing. The gas gauge and Voltage work when c3 is plugged in. 

 

I have checked all plugs to make sure they are clean and intact.I have also checked battery cables and all looks good. After going through this forum i also have changed the VSS sensor in the rear end and it didnt change anything. 

 

I am looking for anyone who may have any info about this issue and maybe how to diag this to figure out the true problem. 

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jlbayes

jlbayes

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This sounds like the truck Motor City Diesel was trying to fix? The next step I would suggest is get the pinout of the C3 and start tracing everything in that connector. I know blue chip told them the vss typically caused it in the past.

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Dooner

Dooner

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Jlbayes  this is the exact truck that was at motor city and I actually brought it there not running so I’m thankful they actually got it running. 

 

I had had my buddy come over with his snap on computer and it did comes up with a p1693 code after all codes were cleared. We then went through and started checking the modules in the interior and found no difference plugged in and not. We did find that ththe cluster was not bolted in and could be moved around fairly easy. Other than that nothing that really stood out. 

 

I am traveling for Work until Thursday so when I get back I will try to provide more details as we were able to get the truck to start with the c3 plugged in but we had to manually ground one of the pins. I have the print out with the exact pin location I will provide that once I get back. 

 

When we grounded the exact pin and started the truck it sounded great but still no gas,temp,voltage,oil gauges. 

 

I will provide more info on Thursday of the exact pin to see if that will narrow it down 

 

thanks 

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Dooner

Dooner

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Thank you for the responses guys!  After looking over my notes it looks like the Pin location is #28   CCD BUS(-)  

 

When we connect a jump ground wire to this pin the truck will run with the c3 plugged into the PCM. It still has no gas gauge,voltage,temp,oil pressure.  

 

Do you guys think this is a grounding issue or a module issue?  Would you happen to have any ideas on the next steps to diagnose this issue? 

 

All help is appriciated! 

 

Thanks 

Quote

 

 

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Mopar1973Man

Mopar1973Man

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Posted (edited)
1 hour ago, jlbayes said:

Check resistance to ground on that circuit using a meter. Key off. Do not have your ground jumper installed.

 

You should have both ends of the wire unplugged and check ohms to ground this will show if there is a connection to ground from a pinched wire or bare wire.

Edited by Mopar1973Man
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jlbayes

jlbayes

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It shouldn't matter with how the bus is wired. It does not terminate at a ground point. He would have to disconnect all of the ccd bus network. The pcm and cluster hold the termination resistors.

Not arguing either with ya Mike. It is a good thought but with the multiple modules on the ccd bus he will be busy finding them all LOL

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Chris O.

Chris O.

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You guys might find this interesting as I am the only few of the ppl I know of that has been reverse engineering Chrysler Collision detection bus (CCD bus) for almost 2 years now.

 

Now this might not be your issue but a possibility,  especially if someone was swapping modules from other Baseline Pickup trucks.

Chrysler PCM horror stories and simple solution

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Dooner

Dooner

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again thanks for the info, I will check the resistance on that pin location tomorrow. Is there a certain number i am looking for?  

 

Also yes the truck does have the overhead console with temperature computer. 

 

After reading the article you posted it seems to me  that would make complete sense as it feels like i have gone over every wire in the engine compartment and under the steering column and i have yet to find a open or shorted wire. 

I can say the PCM was replaced and reprogrammed by the chrysler dealership. I will also try what was described in the article by turning off the VTSS system. 

 

 I will update tomorrow night on my findings. 

 

Thanks

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  • 4 weeks later...
Dooner

Dooner

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On 10/10/2017 at 9:22 PM, Chris O. said:

You guys might find this interesting as I am the only few of the ppl I know of that has been reverse engineering Chrysler Collision detection bus (CCD bus) for almost 2 years now.

 

Now this might not be your issue but a possibility,  especially if someone was swapping modules from other Baseline Pickup trucks.

Chrysler PCM horror stories and simple solution

 

 

Guys i am attempting to do this but i do not have the donor vehicle to test the PCM as the PCM has been changed and i do not have the original. 

 

Where can i find a PCI line to attempt to short to ground?  

 

Thanks

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  • 2 years later...
Schlu42

Schlu42

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On 11/7/2017 at 6:24 PM, Dooner said:

 

 

Guys i am attempting to do this but i do not have the donor vehicle to test the PCM as the PCM has been changed and i do not have the original. 

 

Where can i find a PCI line to attempt to short to ground?  

 

Thanks

Did you ever figure out the problem? I’m having the same issue

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