Wacky ignition switch behavior

[IndyAnne]

I love this forum for all the knowledge here. Thanks in advance!
Problem: it has been raining, don't know if it has anything to do with anything, but...
I picked up a couple of neighbors' trash to take to the dump. Nothing out of the ordinary happened until I got there and turned off the ignition to get out and unload. Truck would not turn off.

Stopped by auto parts store because my go-to guy was closed (Pat Lorber at Apex in Greenwood). Only learned to pull the 30 amp fuse for the ignition EMC ? to stop the engine. When I got home, turned the switch off, but noticed a whining sound from near the gas tank. Scary, so I disconnected the neg. battery line. I put one of those quick disconnect devices because I've been preparing to put in a new stereo and try to troubleshoot the lack of courtesy lights including the dome light.

When I d/c'ed the neg battery, the fuel tank sound stopped. Then I reconnected the neg battery cable. It was still daytime here around 7 pm

later, I went out to get something out of the truck and the dome light was on!

And, coincidentally, the temperature gauge indicates the engine is running hot.

I've been browsing the forum and other sites, not getting much specific info.

Would replacing the switch be the fix? I know the current switch is an after-market replacement because I can't get extra keys made without paying a lot to a locksmith for a "chinese made" (pardon if I'm insulting anyone) key duplicate.

Are the engine temp gauge reading and the overhead light suddenly working possibly coincidental?
Anyway -- why would the overhead light suddenly work when the ignition key will not kill the engine?

[ChevLoRay]

Dizzy.....dizzy......I'm getting dizzy.

This is an interesting delimna. I hope someone with some electrical experience will join in, but in my opinion you have several issues. It sounds like whatever you did to kill the engine didn't take the power away from the fuel pump.

Heck, if I didn't know better, I'd think you're having a problem with your computer.

What you didn't tell us is what year truck you have and how it is equipped. If it is a '96 or newer, a trip to a scan tool is going to be easier to help than an '88-95. Give us some more info and that will help us help you.

[jb1016]

Her truck is in her siggy. And I agree, the whining sound is probably the fuel pump...why would it still be running with the engine off? Weird, wild stuff...

[IndyAnne]

Yes, truck details are in sig.

More clarity: I can turn off and lock the steering wheel and remove the key, engine keeps running.

Instrument cluster gauges continue to work, with elevated engine temp.

Heater/air opens upon starting the engine, and closes when the key turns to OFF and LOCK.

All of a sudden, overhead light is working when it has never worked before.

Fuel pump will continue to run when the key is turned to OFF/LOCK.

Removing IGN fuse (30 amp) is not enough. Have to d/c neg. battery cable also.

That's as far as I've gotten in the differential diagnosis. Chilton and Haynes give good illustration on replacing the lock cylinder, but is that enough?

I'll get the low voltage tester and the multimeter out in the morning and see if circuits are flowing ok, try to narrow down the options.

Previos owner installed the current cylinder from auto parts big box store. Maybe Truck Parts Plus will have a GM replacement I can try.

Other suggestions? I'm not ready to pay a shop's labor cost yet, if I can figure it out would be great.

[ChevyTech]

The ignition switch is an electrical part and is separate from the ignition key cylinder.

The ignition is mounted on the upper surface of the left side of the lower steering column. The high beam headlight switch shares mounting screws with the ignition switch.

A rod going down the steering column connects the ignition lock cylinder mechanism to the ignition switch.

When your replace the ignition switch, your will need to remove the high beam headlight switch. If you do not tape the high-beam rod that goes up the column in place, it will usually fall out. It is not a big problem, but it must be installed correctly for the high-beam switch to function.

Also notice the ignition switch and high-beam switch positions are somewhat adjustable because the holes are slotted.

If I were working on it I would unplug the ignition switch electrical connecters and see if everything turns off.

[IndyAnne]

ChevyTech,

Thank you for explaining the differences. I wish I had a photo, but your directions sound very clear. I'll let you know how I do with getting everything apart. I'll take photos and post those as I go along.

Thanks again.

Originally Posted by ChevyTech

The ignition switch is an electrical part and is separate from the ignition key cylinder.

The ignition is mounted on the upper surface of the left side of the lower steering column. The high beam headlight switch shares mounting screws with the ignition switch.

A rod going down the steering column connects the ignition lock cylinder mechanism to the ignition switch.

When your replace the ignition switch, your will need to remove the high beam headlight switch. If you do not tape the high-beam rod that goes up the column in place, it will usually fall out. It is not a big problem, but it must be installed correctly for the high-beam switch to function.

Also notice the ignition switch and high-beam switch positions are somewhat adjustable because the holes are slotted.

If I were working on it I would unplug the ignition switch electrical connecters and see if everything turns off.