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Tuesday, November 10, 2009

GM Ignition Switch Trouble


Tahoe Steering Wheel above with Air bag module

Tahoe Ignition Switch above with faulty internal section feeding AC/Heater, Cruise Control, 4 Wheel Drive, and Anti-loc brakes

It’s time for another inside baseball episode of auto repair. I ran across a very interesting case yesterday. A customer brought in his 1999 Chevy Tahoe SUV with 5.7L engine. Everything had been fine until he stopped at the store for a moment. When he got back in it to go home a few minutes later the AC/Heater blower, cruise control, 4 wheel drive and anti-loc brakes weren’t working and his anti-loc brake warning light was on. When something like this appears the first step is to find out if all the circuits were being fed from the same power source. They were - the ignition switch to the fuse panel and then to the circuits. The fuses were fine but reading very low voltage as was the power lead from the ignition switch. Since the other power functions were fine from the ignition switch, I figured rightly it was a bad section in the ignition switch. I’m blogging this in case someone out there with one of these vehicles (the Tahoe ignition stayed basically the same well into the 2000’s) would not miss the ignition switch as a culprit. Only a professional should attempt the replacement of this type of ignition switch as it means removal of the air bag module, steering wheel and special tools for the ignition switch fasteners.


14 comments:

Charles Gramlich said...

I wish you lived closer to me dude so I could bring all my car troubles to you.

Middle Ditch said...

All gobbledygooks to me I'm afraid.

BernardL said...

I'm always here for a consult any time, Charles. :)

I get fifty hits a day and at least ten e-mails from my auto repair blogs concerning problems and pattern failures, MD. It's what I do for a living so I try to share some of the potholes. :)

Pat said...

Hi, I have a problem starting my 99 Tahoe. I have a remote starter (not factory installed) and if I use it,the vehicle starts ok.If I use the key in the ignition,it will not start.There are no gage lites on in the run position and the engine cranks ok in start position but wont fire.Once in a while,the gage lites will come on after a delay and the truck starts so I'm thinkimg its a problem in the ignition at the steering column.
Any help is appreciated
Thanks

BernardL said...

Pat, all I can do is take a guess from what you've written. If the remote starter makes it start each time then it would seem probable you have a glitch in the ignition switch. You didn't say whether you have a chip in your key or if it is just a regular key without Pass/Lock. My advice is to have it checked out by your regular tech, but I think you may be right about it being the ignition switch, especially when if the gauge lights come on momentarily it starts.

Pat said...

Hi Bernard,
I have the PassLock but my key isnt chip style.At least manual doesnt say it is.If i fiddle with key in ignition,the guage lights will come on and it will start. Not sure if its the actual key cylinder that is in trouble or whatever it has that contacts the ignition switch,or the switch itself.
Thanks for your input.

BernardL said...

I'm sorry Pat but having a non-factory installed remote start system complicates matters. A tech would need to separate the systems in a diagnostic approach. Once isolated then further tests on the steering column wiring will reveal whether the problem is in the ignition switch or not. You need to have it checked out professionally.

Anonymous said...

Hello there! I just came across your blog and I'm desperately needing some advice. The ignition switch that you posted looks exactly like the one I've purchased for my '97 Chevy S10, so I'm hoping you can maybe help me. I need to put in a new ignition switch that I have purchased, but without thought I just took the old one out without marking or remember where all the wires go. I don't have any mechanical experience at all, but someone had told me this was relatively easy. Turned out, not so much. So, I'm hoping you can tell me where the small white plastic part at the top connects to, and also the bottom black plastic piece. I can not figure it out for the life of me. I'd really appreciate your help or any advice you can give. Thanks so much!

BernardL said...

I'm sorry, Anon, but I don't have any pictures or illustrations of that particular one, and I can't explain what you're asking. My advise is have it towed into a professional. Try looking in your phone book for a mobile mechanic who might be able to help you finish for a price.

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Brandon Paul said...

I have a 99 tahoe. Trying to replace the ignition switch on it. What tool did you use to remove the screws? I have the deep well e4 socket and still can't get to the upper screw to remove it. Is there something I am missing?

Bernard Lee DeLeo said...

Brandon, you have to have a very deep one. They come in a special set, very thin and deep. I also use a long 1/4 extension with wobble tip and 1/4 universal flex adapter on some.

Here's what a deep one looks like: http://www.amazon.com/CTA-9578-Ignition-Switch-Socket/dp/B00FQSP3SA

If you have one this thin and deep, you need to figure a way to approach it.



Unknown said...

I'm having an issue with the ignition switch in my 99 Tahoe as well, started with trouble code p0751, 2-3 shift solenoid.... After replacing all 4 solinoids (for good measure) truck still had same issue. By default transmission automatically goes into 3 gear. After researching I learned that the ignition switch was the culprit. I replaced the switch and now it will crank crank crank but won't turn over.... I also have passlock (not sure if it's one two or three) but no chip in the key. Any ideas?

Bernard Lee DeLeo said...

Unknown, I'm sorry but in a situation like yours, you need to start with the basics.

1. Make sure the ignition switch is OEM and looked up by VIN number to make certain it's the right one. If the passkey system was causing it, the vehicle wouldn't crank.
2. Check for strong spark at the plugs. It won't start without it.
3. Check for Fuel Pressure.

If it was starting before you did the ignition switch then because I don't believe in coincidences, my first pick would be number one - you either bought a cheapo aftermarket ignition switch or you got the wrong one.