Boujii

Hello my new friends

I have here a 2008 Chevy Cobalt that is throwing a U0100 code. I am not getting crank when turning the key. Also the fuel gauge doesn't move when in the 'on' position and also usually see 'power steering'. The results vary when I turn the key to crank position. Sometimes the dash won't change. Right now when I crank all the lights go out. It's almost like a bad ground. I have manually grounded the chassis of the ECM to the chassis and engine grounds, but no luck. I have taken the ECM out and looked at the connections in which they look fine to the naked eye.

I found two fuses under the hood for ECM. One is a 15 amp fuse marked ECM and another is a 20 amp fuse marked ECM/PCM. The 15 amp fuse tested fine and I am getting 12 volts from the left leg of the fuse. However the 20 amp marked ECM/PCM is not getting any voltage at all. These tests was done with the key in the ON position.

I have checked the battery terminals and they look fine. I even unbolted them and rebolted them.

I have not taken the ECM apart yet to look for burnouts. I wanted to diagnose this 'no voltage' to the fuse before doing so.

Anybody have any suggestions or comments?

Thanks a bunch

Edit:
Here is the VIN details in case it helps.
http://www.vindecoder.net/?vin=1G1AL...&submit=Decode

GMRatchet

Check grounds under surge tank. Also check that the engine wire harness has not been rubbed through were it runs near oil filter housing.

Boujii

I ended up buying a used ECM/PCM from ebay that was pre-programmed to my vin with the latest flash updates.
Worked like a champ.

The only thing not resolved is the 0315 crankshaft needs to be relearned. I believe this needs to be done with a tech 2 scanner which I don't have.
The code does not affect anything though.

ENGINE COMPUTER PROGRAMMED CHEVROLET COBALT 2007 2008 2009 2010 12612397 OEM | eBay

Tdubbs

Any shop with a scanner should be able to do the relearn procedure.