2008 V6 Silverado won't turn over

[hgoodwiniii]

Hi all, I am new to the forum and need some help.

 

I am having trouble where my 2008 Silverado 1500 won't turnover with the key in the crank position. When I turn the key to the "on" position, all gauges/ gauge lights in the instrument cluster activate. When I turn the key all the way forward to the "start" position, all gauge/ gauge lights in the instrument cluster go blank. That includes the 'anti theft/security" light.  I have had the battery, ECM  and starter/solenoid tested. They came out fine. I have put a test light on the starter solenoid wire connector and there is no power there with key in the crank position. I did an OBD scan and I am getting code U0100 ( Lost Communication with ECM/PCM). 

 

Anyone have any thoughts what the problem may be and what I need to check next?  Thanks.

 

Edited November 30, 2022 by hgoodwiniii

[richard wysong]

I would start by checking voltage drop on aii battery and ground cables. Does it crank over if you jump the starter or starter relay? See posts by robert24b, newer truck but some info there

Edited November 30, 2022 by richard wysong

[CamGTP]

Almost always is a bad connection problem somewhere if everything goes blank.

[hgoodwiniii]

 

6 hours ago, richard wysong said:

I would start by checking voltage drop on aii battery and ground cables. Does it crank over if you jump the starter or starter relay? See posts by robert24b, newer truck but some info there

 

Ok, thanks. I will try to jump the starter over to see if the engine cranks today. Thanks. 

[Douglas Nathan]

You always have to consider bad ground(s); when I find a ground I wire brush the ground point, fastener and the terminals on the wires that go there and apply DI-electric grease to all contact points to inhibit further corrosion. I even put the grease in those connectors with the 3 lips  on them. I do not know if ANY grease is better than NO grease but I do know that any automotive grease will keep water out of the connection. The grease might be conductive, I donno. DI-electric grease is purpose formulated to protect electrical contacts from the environment.

Edited December 2, 2022 by Douglas Nathan