SWAG: remove and check/clean the PCM/ECM connectors.
Help! My Tahoe won't shut off!
- Thread starter angeleyez_2306
- Start date
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Hi Fless, thanks for the response. I had the ECM inside on the heat register overnight & blew all connectors with Nitrogen & Cleaned with contact cleaner, No luck. It seems like the ECM may be failed. When I unplug it the PWR/TRN relay drops out. This is the relay I pull to shut the truck off.
Has the relay been replaced with a known good relay?
Yes, as soon as I put the relay in it clicks and turns on. I have to pull it to stop the truck and then disconnect the battery or it drains the battery. Truck drives fine I just can't actually stop the engine without pulling the Relay.
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Why would you pull the relay if you can stop the engine without doing that? Confused...
I can't stop the truck, that is why I pull the relay.
Wow this is freaky! 
wjburken
Supporting Member
My 2007 Silverado had a bout of odd glitches like this where the headlights wouldn’t shut off without pulling the fuses and the horn started going off whenever the truck was turned off. Ended up being a badly corroded fuse block under the hood. Replaced that and everything went back to normal. Might pull that and take a look underneath.
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Seems like the GMT900 fuseboxes can have that issue. I had forgotten about that.
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