2004 GMC Envoy P1680 reading

BREXMOM

MEMBER
2004 GMC ENVOY
6 CYL
2WD
AUTOMATIC
58,000 MILES

My "check engine soon" and "reduced engine power" lights come on. When this happens it feels as if the vehicle goes dead; however, it doesn't but I find myself having to coast into the closest parking lot to avoid being hit. Each time it's done this I have taken it to 2 different autozones for them to check it out. Both times the hand held system comes up with this P1680 reading. When they look the code up it tells them ECM failure. The part even refurbished runs $460 with a core charge. I'm trying to decide on if I should go with these 2 readings or actually take it to a dealership and have them put the vehicle on an actual diagnostic machine. A co-worker told me it also could be the fan motor harness. Any suggestions?

4 Replies

BRIAN 1

MECHANIC
1,030 POSTS

You should take this vehicle to the dealer. Autozone is not a place to take your vehicle to be fixed or diagnosed. People at autozone sell parts they dont fix vehicles. Dont put an ecm in this vehicle without proper diag.P1680 is an accelerator pedal position code. Here is a bulletin that might help. Service Engine Soon Light On, P1680 (Reprogram or Replace PCM)

Models: 2004 Buick Rainier

2004 Chevrolet Trailblazer

2004 GMC Envoy

2004 Oldsmobile Bravada

with 4.2L Engine (VIN S - RPO LL8) Some customers may comment on the Service Engine Soon Light coming on. Upon investigation, the technician may find a P1680 diagnostic trouble code.

Correction
Check the resistance of the accelerator pedal position sensors using the procedure in the appropriate Service Information for DTC P1680.

If the resistance of the accelerator pedal position sensor is within the specifications shown in the Service Information and the vehicle was built prior to the following VIN breakpoints, then reprogram the PCM with the latest calibration.

If the resistance of the accelerator pedal position sensor is within the specifications shown in the Service Information and the vehicle was built after the following VIN breakpoints, then replace the PCM. If the resistance of the accelerator pedal position sensor is outside the specifications shown in the Service Information, then continue with the diagnostics for DTC P1680. VIN Breakpoints

"� Vehicles built at Oklahoma City Assembly Plant - 46192755

"� Vehicles built at Moraine Assembly Plant - 42315833 post back with what you find. My advise take it to a professional.

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Thursday, August 14th, 2008 AT 7:27 PM

BREXMOM

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2 POSTS

Brian,

Thank you for your reply.

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Friday, August 15th, 2008 AT 7:21 AM

BEATRICE HERNANDEZ-GARZA

MEMBER
1 POST

I had this same code come up on my Envoy Today. The check engine light came on and stalled out a couple of times. My husband noticed the gas cap was loose. He tighten it up. Turned the engine off and on, and the check engine light went off. I hope that's all it was. If that was all it was. Im just imagining how much I would have paid a mechanic to replace parts that don't need to be replaced? Smh. Good luck. Check your gas caps first.

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Wednesday, May 17th, 2017 AT 10:26 AM

SATURNTECH9

MECHANIC
30,870 POSTS

A loose gas cap won't cause a stall or that code it's a far more serous problem then a loose gas cap. There is a fault in the throttle by wire system.

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Thursday, May 18th, 2017 AT 6:20 PM