There is a printed circuit board directly below those fuses and relays , There could be a faulty foil trace that feeds the unpowered fuses .
It is more likely that than a bad ECM . What you need to do is have an actual wiring diagram that also shows the circuitry on that board from first point of entry to final output of the wiring harness .
Or trip to the junkyard to get a used fuse block from a like donor vehicle ….

 

Ok, thanks; So I will pull the underhood casing that holds the fuses and relays and check the circuit board underneath that casing, correct?

 

That is what I would do based upon your observation of a lineal failure to supply voltage to a row of fuses . Keep in mind you might need a magnifying glass to see where the foil is cracked or broken . It could also be a bad solder joint on the supply terminal for that row of circuits .
Heck you might even get a part number from the circuit board . Best of luck and Patience is your friend on this project .

 

Ok, thanks. I will check it out and report back.

 

Hey man, I’m having the same issue. Have you gone any further?? Have you figured it out yet? I’ve tried everything I can think of.

 

Hi Btyree26 - No, I'm still stuck. I have not figured it out yet. I had to stop working on it because of foot/ankle surgery. I did pull the underhood fuse box like rcorn1031 suggested but I did not see a printed circuit board underneath on my 08. There's only wires and connectors only underneath mine.`

https://www.gm-trucks.com/forums/top...errors/page/2/

https://m.youtube.com/watch?v=Y6nTQ_mZn14

https://m.youtube.com/watch?v=2-qnsfC5o7Q
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I will definitely give an update when I get it figured it out. Please do the same if you figure it out before me. Thanks.

 

Finally - got it figured out; Took it to an electrical shop. They found that both the ECM and BCM were out on the truck. I didn't believe it that both could possible be out at the same time at 1st but the shop gave me the old parts and I reinstalled them one at a time and the vehicle was back to not starting. I put them back and it runs fine.