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Juan Crespo
Juan Crespo, ASE Certified Technician
Category: Chevy
Satisfied Customers: 1526
Experience:  A.S.E. Master Technician, Advanced Level, Emissions - Asian, Domestic, & European
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I have 2008 Uplander with U0100 DTC code. No crank

Customer Question

I have 2008 Uplander with U0100 DTC code. No crank
Submitted: 1 year ago.
Category: Chevy
Expert:  Juan Crespo replied 1 year ago.

Hi there. Thank you for using our service.

U0100 is set when there is no communication via serial data from the PCM to the other modules in the vehicle. This could happen if:

  • The PCM is not the right one for the vehicle
  • The PCM is not programmed to the vehicle - must be a match for the vehicle's VIN
  • The PCM is not powered or grounded properly

What kind of diagnostic tools do you have access to?

Customer: replied 1 year ago.
Autel DS708
Expert:  Juan Crespo replied 1 year ago.

I'm not familiar with that scan tool. Can it get serial data from the vehicle?

Also, did you make sure the replacement PCM had good power and ground and that it was the right part number for the vehicle and that it was programmed for the vehicle's VIN?

Customer: replied 1 year ago.
The check engine light doesn't come out. Currently the car have his own original ECMI checked all the fuses, the relais, the DLC. It showed me nothing wrong. I also cheched the continuty from the stater to the ECM.
Customer: replied 1 year ago.
I already left the shop. I can give vin number tomorrow if that work for you
Expert:  Juan Crespo replied 1 year ago.

You didn't answer my question regarding your Autel. I don't think I can help you any further if you don't have access to a scan tool that can read serial data from the modules.

Best Regards.

Customer: replied 1 year ago.
What did you mean by the serial data?
Expert:  Juan Crespo replied 1 year ago.

Serial data is how the different modules communicate with one another. In your specific case, code U0100 is telling you that the PCM is not communicating with the other modules, which means there is no serial data being received or sent by the PCM. Attached please see the serial data schematic for the 2008 Uplander.

I've never even seen a scan tool such as the one you have, but according to their web site the Autel MaxiDAS DS708 is capable of communicating with all the modules in the vehicle, identify the VIN and even reprogram the PCM.

In your original question, under Already Tried you wrote "Replace the ecm". Just out of curiousity, what diagnostic path led you to replace the ECM?

Customer: replied 1 year ago.
I juste replaced the ECM I thought it was the probleme. But since the replacement didn't made any change. I reput the one for the car in place.
Customer: replied 1 year ago.
The probleme came because they tried to jumpstart after the car battery was dead.
Expert:  Juan Crespo replied 1 year ago.

We're back to the matter of using a capable scan tool to properly diagnose this issue. Other than that, you can check all the powers and grounds going to the PCM to see if something got fried during the jumpstart.

Best Regards.

Customer: replied 1 year ago.
I will do it and let you know.
Customer: replied 1 year ago.
Hello
Expert:  Juan Crespo replied 1 year ago.

Hello.

Customer: replied 1 year ago.
I'm cheching the battery voltage courent and the ground. I will texte you when finish
Expert:  Juan Crespo replied 1 year ago.

OK.

Customer: replied 1 year ago.
Good ground. But there is not power in the red/white wire battery voltage
Expert:  Juan Crespo replied 1 year ago.

Can you tell me the wire location? Connector and pin number? Are there any other problems with ground and power key off and key on?

Customer: replied 1 year ago.
Sure
Expert:  Juan Crespo replied 1 year ago.

???

Customer: replied 1 year ago.
Ecm connector X1 end. Pin location 20, circuit 540
Expert:  Juan Crespo replied 1 year ago.

So, there are no problems other than circuit 540 not having power?

Customer: replied 1 year ago.
Customer: replied 1 year ago.
I just start the car. Thank for your hint.
Expert:  Juan Crespo replied 1 year ago.

Glad to be of help. What did you find, a blown 15Amp fuse or a broken wire?

Best Regards.