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2007 Avalanche with U0100 Lost comunication with ECM/PCM A.

Notchpedro

By Notchpedro
in Ask A GM Technician

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Notchpedro New Member

Notchpedro

Posted
Posted

Got a bit of a problem with my 2007 Avalanche 5.3

 

Got one code: U0100 - Lost comunication with ECM/PCM A.

 

Wont even crank.

Also got Service stabilitrak, service traction control, park assist off.

Fuel gauge dont move at all, stays at the bottom. (tank is half full)

 

Got 60 ohms at the diagnostic port.

Checked the 5V reference points and I got less than 1V on all three. (map sensor, maf and tps)

 

Starter is fine, have removed it and tested it.

Have replaced the negative and positive battery cables and have tried with 2 other batteries.

 

Is replacing the ECM/PCM the next step or am I missing something?


 

 

Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

Keep a meter on your 5v reference, and start unplugging sensors one by one. You might have one shorted that's bringing the entire reference down. Once it goes back to 5v, it'll start.

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