Truck continues to run after turning off ignition switch

I have a 1999 K1500 truck that is having a very odd problem. Last week, I was on the road and stopped to get gas. When I turned off the ignition key, the truck continued to run, but all of the dash lights went off and the Check Engine light came on. Also, once the ignition key was off, the truck was idling so low that I could hardly tell it was running. When I went to turn the ignition back on, the check engine light went off and the AC blower fan came back on. In addition to the truck still running when the key is off and out of the ignition, I also lost all of my trailer lights and parking lights. My turn signals, brake lights, and hazzard lights still function properly. My first thought on this problem was that a relay is hanging up; however, I am not sure where to even start looking for which relay it might be. Any help would be sincerely appreciated.
Do you
have the same problem?
Wednesday, January 31st, 2007 AT 4:47 PM

1 Reply

Sorry for the late reply.

I'd have to check primary voltage at the ignition coil. There shouldn't be any primary voltage at the coil with key off, if there is voltage, either something wrong with ignition switch or that circuit is shorted to voltage, somewhere.

Another thought is it might be dieseling caused by high cylinder compression or maybe a hotspot in the cylinder. Usually with dieseling, the idle is rough.
Was this
Thursday, March 19th, 2015 AT 9:32 AM

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