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My car will not start

Tiny
ERICSCHROEDER
  • MEMBER
  • 2007 CHEVROLET COBALT
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 48,000 MILES
The battery drained when the lights were left on overnight. So I jump started it and it fired right up. Later in the day I tried to start it and got nothing. I got the battery tested and it was fine. I took the starter out and got it tested and it was okay. We hooked up a scanner to it and we got "U0100 lost communication with ECM, PCM a". Does this mean I need to replace the ECM? I am getting power to all of my lights and stereo. Any help would be appreciated!
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Sunday, September 27th, 2009 AT 1:23 AM

6 Replies

Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
This sounds like you had a voltage surge when jumping the battery that weakened a fuse did you check them all? Here is a guide to help us guide started:

https://www.2carpros.com/articles/how-to-check-a-car-fuse

Check out the diagrams (below).

Please let us know what you find.

Cheers, Ken
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Tuesday, July 17th, 2018 AT 11:15 AM
Tiny
ERICSCHROEDER
  • MEMBER
  • 4 POSTS
We tested the small wire at the solenoid and it was not getting anything with the key on start. What does that mean? Thank you for responding also!
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Tuesday, July 17th, 2018 AT 11:15 AM
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
It can mean the system is not seeing the initiation of the ignition key.
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Tuesday, July 17th, 2018 AT 11:15 AM
Tiny
ERICSCHROEDER
  • MEMBER
  • 4 POSTS
That would give a u0100 code?
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Tuesday, July 17th, 2018 AT 11:15 AM
Tiny
DOCFIXIT
  • MECHANIC
  • 18,828 POSTS
Yes, if fuse ignition switch/PK3 in BCM located under center dash right side console.
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Tuesday, July 17th, 2018 AT 11:15 AM
Tiny
ERICSCHROEDER
  • MEMBER
  • 4 POSTS
I checked the fuse and I replaced it with a spare. Now the car starts and runs great Thanks 2Carpros, I love this site.
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Tuesday, July 17th, 2018 AT 11:15 AM

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