'03 Envoy will not shut off. Not the ignition switch. Need Help!

[ETicket]

I need some help. I have a 2003 GMC Envoy SLT 4x4, I6 engine with 148k on it. It will not shut off. I have changed the ignition switch twice, checked the second new one with a test light to determine it was not the culprit.

It started as I walked out to get into my truck and noticed the check engine light was on before I even put my key in the ignition. I went to crank it over and it was dead, so I jumped it and I started right up, but it would not turn off. I finally pulled the fuel pump fuse to shut it off. I researched the issue and it seemed the ignition switch was a likely issue so I changed it, and the same problem existed. I replaced it a second time hoping the new one was at fault, but the same issue persisted. I put a test light to it and determined the switch was good.

To further add to this mystery when I do start it and take it for a drive, 90% of the time the transmission will not shift automatically, I have to manually move it through the gears or it will just try to lug out of Drive (I am assuming 3rd or OD).

I am at a complete loss here.....and expert advice as to what to look for next?

Thank you!
-Eric

 

[BlazingTrails]

I have not had to deal with the ignition switch yet, but I have heard that they are adjustable. There is some kind of gear you have to set in the switch. Maybe you can Google it, I would post a link but I am at work....

 

[ETicket]

Thank you for your response. You are correct in that the switch does need to be timed. I have done so, I've matched each as I have replaced them, and double checked by timing the key release mechanism.

 

[Mike w]

gm part 88965342 try that should fix the problem

 

[ETicket]

Thanks Mike w. I also thought of that so I used the switch outside of the case/cylinder. Moving the gears to the off position still did not result in shutting the vehicle down.

 

[Mike w]

Ok bear with me. Quick question can you shift out of lark without touching the brake?

Park*

 

[ETicket]

No, the transmission safety remains engaged until I press on the brake pedal (normal operation).

 

[Mounce]

Glad you made it over here, welcome to the Nation! I had also thought of the ignition switch being misaligned. The only other thing that I can think of that would cause such a problem would be a mishap in the pcm.. But I don't have idea why or what would cause that. Someone else will chime in soon, good luck.

 

[ETicket]

Thank you! ....yeah, this one really has me stumped!

 

[budwich]

what electrical "appliances" have you installed (ie. non-stock equipment)? It would appear that you have "run voltage" which being distributed from somewhere other than your switch causing the PCM to remain "active" and keeping your vehicle running.... that's why the "CEL" light was on.

 

[ETicket]

No aftermarket accesories, Envoy is completely stock. I drove it to the park the day before with the kids, parked it in the driveway, came out the next morning an the light was on before I even inserted a key.

 

[KNBlazer]

A stuck relay? I have no clue, tap some relays gently with a screwdriver and the engine running with ign to off, far fetched, but who knows....

 

[Mike w]

I also suspected the truck had a short somewhere and the retained power feature is interfering.... but it would shut off as soon as you open the door am I right?

Relays could be a possibility knblazer

Your CEL was on because the ignition was still on the code was most likely for low voltage.

 

[KNBlazer]

@eticket, have you had some recent work done, like in the last 2 weeks or so...

 

[ETicket]

No, I haven't had anything done at all. Last thing that was done was an A/C Pressure switch since the A/C was cycling on and off above 88* F. I did that myself...and it did not fix the problem. Other than that there has been no service on the vehicle since the Fall.

 

[ETicket]

Okay fellas, I think I may have solved the mystery. After you all mentioned the relays, I figured I would pull each from the fuse box and re-seat. Well, sure enough once I did it no more issue. I am hoping that this does not manifest again, but for now I am marking this on SOLVED!!

I really want to thank all of you that responded...It really got me thinking, and made me look at it over again!

Thank you!!

 

[Mike w]

No problem glad its fixed.

 

[RayGumm]

It will very likely resurface, it's either a faulty relay or faulty wiring beneath the relay. Next time it happens try to isolate the relay that is the culprit by checking one at a time. You can already rule out fuel pump relay because you pulled that one to kill the truck. Process of elimination, brother! Good luck and happy to hear it is working for the moment and you have it narrowed down to what the gremlin is!

Also, Welcome to the Nation!

 

[ETicket]

Thank you Ray...glad to be here!!