Still running even with key out of ignition?

[tirwin88]

I have a 2003 Trailblazer ext. Yesterday when returning home I turned the truck off and took my key out. I noticed that when I opened the door my radio was still playing. Then I noticed my car was still running! I got back in and put the key in the ignition, turned it, and it did nothing. I then put the car in reverse and it shut off. Then my check engine light came on while the car was off! I tapped the brake and the check engine light went off. It did this several more times last night as I was testing it. Now today my check engine light is on when driving and when I turn the car off it shuts off but the check engine light comes on again when the car is off. I tap the brake and it goes off. Any ideas?

[maxwedge]

Could be a bad ign switch they were a common failure. Also check for burnt wires under the dash coming out of the column. Also check what codes are stored.

[tirwin88]

Ok so after starting the car this morning and for some reason something drained the battery, my key was now stuck in the ignition. I had to jump the vehicle. The engine light was now off I am assuming it reset itself from the battery being completely drained. I then turned the car off again and took the key out, the engine again was still running, I tapped the brake and the car shut off but all of my lights on my dash came on (ie check engine 4wd etc) then they all went off except the check engine light. I tapped the brakes again and the check engine light blinked off but came right back on. Then the brake would not allow me to tap it anymore as it locked as was the steering wheel etc. I started the car back up and took it to the shop to have the codes pulled.

The only codes they pulled were p0740, po785, and p186 which they told me were transmission codes and I would have to go to a transmission dealer! I feel nothing wrong with my transmission and other then the light coming on when the car shut off, that is the only time I ever saw it on! Any ideas?

[tirwin88]

After replacing the ignition switch as was recommended, the car still continues to keep running when I turn the key to the off position and pull it out. It doesnt do it every time. But the engine light continues to come on after I turn the car completely off and will not go off until I tap the brake several times. When you tap the brake you can hear a clicking noise coming from one of the parts sitting under the hood. We could not figure out what this part is. We disconnected the wires running to this part and tapped the brake. The engine light did come on but the tapping noise ended. I will get a picture of this part under the hood where the clicking noise is coming from and post it. We started the car while this was unplugged and the reduced engine power light then came on. Does anyone have any idea what is happening here?

My friend has been working on cars for quite some time and is at a loss as is everyone else I have spoken with. It is still throwing up the Transmission codes.

[maxwedge]

"Could" be the switch is not a recommendation addt'l diagnosis is always required with electrical issues, you will not track this down without a factory shop manual /wiring diagram to look at the affected circuits for what is happening.

[tirwin88]

Thanks Max.

As luck would have it, my friend was able to locate the issue. The Stop Light Switch was bad which was somehow causing all these issues. Replaced the stop light switch and havent had a problem since.

[manicmechanix]

What's funny on late models with the BCM is a bad switch can make other circuits act funny sometimes. I'm not saying that's was the case here with this brake switch, but something I've noticed .