Ignition

[jarheadcapt]

I have a 2004 GMC Sierra 2500 HD 4WD w/ automatic transmission that when you turn the ignition off the truck remains running and will accelerate. Also the wire for the coil was disconnected to turn the engine off and reconnected.

 

1st thing what would cause the engine to remain running and secondly when it was restarted and driven it will not shift out of low gear. I should probably tell you that this truck is a friend of mine's and I do not know alot of it's history and I believe it's a 2004 give or take a year.

[8.1HD/ALLISON]

Does it have an aftermarket remote start or security system. I have seen them installed wrong and cause the vehicle to keep running after shutting key off.

[jarheadcapt]

Does it have an aftermarket remote start or security system. I have seen them installed wrong and cause the vehicle to keep running after shutting key off.

 

 

 

No. He has no after market starter but I think he has a factory security. I was thinking it was the ignition tumbler but when the transmission wouldn't shift I began to wonder if it was more of a computer issue. I just got of the phone with him and he says it did it once last fall when he went to work and he just locked his truck left it running and when he came out for lunch it had shut itself off. Let's just say he's not the brightest bulb in the bunch. The only thing that had changed was that he had the connector plugs for his Boss plow rewired. But I can't figure out what that would have to do with the ignition.

[minibike132]

Best guess is an ignition switch.