Please help... I recently replaced my ecm because I believed that it was not sending current to prime my fuel pump once you open up the ignition switch. I installed the new ecm, opened up the key and right away started getting messages on my dash that I had not received before. Service 4x4 and also service charging system. As instructed I tried to perform the anti theft programming but after completing the steps, I turned the ignition into crank mode and nothing happened. Not a click, no sound at all.. I tried the anti theft programming a lot of time with no luck. So I tried installing the old ecm to see if the new one was faulty and now the old ecm doesn’t crank or do anything when I’m turn the ignition switch. What’s funny is that now the old ecm primes the fuel pump and it wasn’t doing that before..
I tried connecting a scanner to see if I could pull any codes but all I get is an error message on my scanner. I have checked all the fuses and everything tests out fine. Any other ideas that could help me figure this out?
By the way, before installing the new ecm, the truck would crank but it wouldn’t start since the fuel pump was not being engaged..
Thanks In advance .

 

I have a 08 silverado that I am experiencing the exactly the same issues you were having. I'm hoping you might have found the solution by now? Thank you in advance for any and all help you can provide me with.
Thanks, Brandon
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