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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), GMC Mechanic
Category: GM
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2007 GMC Denali 6.2 not the XL with 170K ***** *****, Engine

Customer Question

Customer: 2007 GMC Denali 6.2 not the XL with 170K ***** *****, Engine light came on, switched truck off, engine light stayed on. Came out next morning battery was dead, had battery tested it was completely gone, replaced battery with heavy duty battery. Started truck, started with no problem but would not shut down when I switched it off and engine light was still on, took the key out and the truck was still running even with key out of ignition, had to remove the engine control relay to get it to shut down. Went on vacation for a week and a half removed the cable from the battery before I left to make sure the battery did not drain with the engine light on. Reconnected battery cable todaya week and a half later after disconnecting it and truck started fine with no lights and it shut down without incident, 10 minutes later, it went back to normal behavior with engine light on. I did notice today that it did shut down, but it struggle to switch off, the engine light would fade away somewhat but not completely go out and when I hit the remote lock the engine light would fully illuminate.
JA: Thanks. Can you give me any more details about your issue?
Customer: Name is ***** ***** the above info is all I have
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Submitted: 10 months ago.
Category: GM
Expert:  GM Tech (Cam) replied 10 months ago.

Tony, I am Cam.

To start with, do you have ANYTHING aftermarket installed at all?

Customer: replied 10 months ago.
No
Customer: replied 10 months ago.
P1682 code
Expert:  GM Tech (Cam) replied 10 months ago.

Ok, have you tried swapping out the relays for the powertrain with others of the same numbers in the underhood fuse block? Its possible that the contacts are sticking and causing this.

If no, please do so. Also inspect for signs of corrosion in the underhood fuse block as well.

Customer: replied 10 months ago.
One thing I did notice tonight when I went to the truck to get something out, when I use the remote to lock the door, the engine light comes on and also the key symbol was illuminated. When I hi the unlock the engine light went away. I will try switching relays tomorrow morning.
Expert:  GM Tech (Cam) replied 10 months ago.

Also check the ground wires. This sounds like power is being diverted from some circuits to others. There are grounds down on the engine block, on the frame under the drivers door and on the cylinder heads. Make sure all those are clean and tight.