Multiple Issues

[STL_G8GT]

https://www.gmpartsdirect.com/auto-p...umber=92262410

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#7 or #11

Here's ignition switch elec info

Ignition Switch Elec.pdf


Here's ignition switch R/R info

Ignition Switch RR.pdf


Here's the ignition barrel info. Beware of SRS system, as always. I saw two ways to disable it, fuse removal, or remove negative battery cable and wait 1 minute before any work begins.

Ignition Barrel.pdf

[SpaceFrank]

Awesome, thanks!

[Napalm]

odd but have you replaced the batteries in your fobs lately. I know when mine get weak it doesn't want to lock and unlock right. I don't get the other issues but it could be low enough that the anti-theft chip loses connection to the car.

meanwhile on the other hand have you checked your fuses all your fuses. and see if there is a weak one. I could see where - cold start up - all well - heated up there is the beginning of a gap - then bump - loss of power. then reconnected then bump - loss of power.

I could also see a frayed wire in the mix just as easily.

Do you have issues putting the key in the cylinder?

[SpaceFrank]

I let this sit for a while since I have another car to drive and always dread electrical troubleshooting, but I finally got around to poking at it over the holidays.

I could only get the upper column trim cover off without removing the steering wheel, but luckily I didn't need to remove the lower trim cover to get access to the wiring and harness connectors in question. I fiddled with everything, both idling in the driveway and while driving around town. (I removed the airbag fuse first, for obvious reasons.) Jiggled all the wires and connectors inside the column that I could reach, and jiggled the ignition key. Nothing happened like before; no symptoms at all.

I drove around for 10-15 minutes; where I live there is no shortage of potholes and speedbumps. I was only able to get something to happen one time, when I hit a particularly sharp bump at 30-40 mph. The door locks cycled and the dash lights/stereo died for a half second. Engine stayed on. Couldn't get it to repeat on any other bumps. Nothing at all when slamming on the brakes.

Now that being said, I have driven the car a couple times since my friend and I fiddled with it back in September, and I got fewer or no symptoms those times either. In particular, I haven't been able to kill it by jiggling the ignition key since that one time. So the issue didn't just get better all of a sudden. Maybe it's weather related? Best I can guess is there are multiple potential causes, but all variable with time, temperature, or something. Keep in mind last year it also stopped doing the transmission limp mode thing for no apparent reason as well.

Now I'm back to thinking it's the BCM. I'll probably go poking at the connectors on that tomorrow. Any way to diagnose whether the BCM itself has gone bad?

[SpaceFrank]

Today I pulled the lower dash panel and went poking around the BCM with the engine running. Jiggled all the harnesses and connectors, tapped sharply on the BCM itself. No symptoms at all.

Went for another test drive and got the electrical drop-out symptoms a few more times, on smaller bumps this time. I did notice one important thing: the transmission does shift into neutral whenever the door locks cycle. I'm not I'd explicitly confirmed this before since I normally get off the throttle when I hit a bump. This time I definitely noticed RPMs increase when I hit a small bump while pulling away from a stop sign.

So at this point I'm thinking it has to be the TCM, especially considering the past issues with it going into limp mode or not wanting to shift into reverse after sitting for a while. While the ignition switch might be a separate issue, I think it was a red herring for the most part.

Just to be sure before I order parts, is there a separate ground strap for the transmission that might be loose? I've wiggled the big electrical connector on the transmission to no effect, and I don't see a separate ground anywhere, but I might have missed it.

[SpaceFrank]

It's been a while, and I haven't done any work on the car except replacing the starter. I never installed the heat shield after doing the engine swap a few years ago, and I was probably baking the original starter with heat from the headers. I started having random issues where it would take a few turns of the key to start, which progressively got worse. While I hoped a bad connection here might've been causing my other issues, that wasn't the case. Wire connections at the starter were all tight. I installed a new ACDelco starter (and put on the heat shield this time); while the car now starts up much quicker and easier, I still get the random occasional dash/transmission dropouts.

One thing I hadn't mentioned before is that it sometimes has the same symptoms when taking a hard right corner (I've never noticed it doing this on a left turn). It's been doing this randomly for a while, but last week when I decided to take a hard right under power, the car died completely, engine and all. The engine wouldn't restart afterward, and I also couldn't removed the key from the ignition. After coasting into a parking lot and shifting into Park, the shifter was also locked in place. I tried disconnecting the battery for 15 minutes, but that didn't change anything. Key still stuck in ignition, although I could turn it all the way to the start position. No matter what position the key was in, the only indications of electrical power anywhere were the blinking red light on the dash... and a new indicator in the instrument cluster, a padlock around a car. Apparently I've activated some kind of security lockout.

I had to have the car towed home, where it now sits. I suppose I've narrowed down the cause of my problems to the security system, but I'm still not sure how to proceed. And now the car is completely undriveable. So I have two questions.

1. How do I reset the security system to remove the key and/or start the car again?

2. Where should I start looking for signs of an electrical fault? I've already poked around inside the steering column to no effect. Does this car have some kind of tip-over switch?

[-Ray-]

You need a volt meter to check the places where you should have 12 volts. Check continuity at the fusable links.

[STL_G8GT]

You might try to email Chris White. He might be able to tell you what is common amongst all of your diagnosing and effort. In my mind, the fact that you, at one point, were able to jiggle the key cylinder and get the effects to happen point me to that area. The security module is in there as well.

It's been a while, and I haven't done any work on the car except replacing the starter. I never installed the heat shield after doing the engine swap a few years ago, and I was probably baking the original starter with heat from the headers. I started having random issues where it would take a few turns of the key to start, which progressively got worse. While I hoped a bad connection here might've been causing my other issues, that wasn't the case. Wire connections at the starter were all tight. I installed a new ACDelco starter (and put on the heat shield this time); while the car now starts up much quicker and easier, I still get the random occasional dash/transmission dropouts.

One thing I hadn't mentioned before is that it sometimes has the same symptoms when taking a hard right corner (I've never noticed it doing this on a left turn). It's been doing this randomly for a while, but last week when I decided to take a hard right under power, the car died completely, engine and all. The engine wouldn't restart afterward, and I also couldn't removed the key from the ignition. After coasting into a parking lot and shifting into Park, the shifter was also locked in place. I tried disconnecting the battery for 15 minutes, but that didn't change anything. Key still stuck in ignition, although I could turn it all the way to the start position. No matter what position the key was in, the only indications of electrical power anywhere were the blinking red light on the dash... and a new indicator in the instrument cluster, a padlock around a car. Apparently I've activated some kind of security lockout.

I had to have the car towed home, where it now sits. I suppose I've narrowed down the cause of my problems to the security system, but I'm still not sure how to proceed. And now the car is completely undriveable. So I have two questions.

1. How do I reset the security system to remove the key and/or start the car again?

2. Where should I start looking for signs of an electrical fault? I've already poked around inside the steering column to no effect. Does this car have some kind of tip-over switch?

[SpaceFrank]

I forgot to update this, but my buddy and I found the source of the lockout and power loss. The big fusible link coming from the positive terminal under the hood had broken. I cut out the remains of the fusible link, crimped on some terminals, and mounted a heavy-duty fuse of the same rating (175A) in a little fuse holder on the inner fender.

I hoped it had been slowly failing and causing my intermittent issues, but apparently not. The car is now driveable again, but I still get dropouts when I hit hard bumps or take a hard right turn. I've verified the fuse and related connections are still good.

I can't see how that fusible link could've failed from overcurrent, so I'm guessing it was a mechanical failure. Maybe I bent it while doing the engine swap, and it fatigued over time since it was basically hanging out in space. At this point I'm worried about what else in the harness I might've tweaked. I do need to look back into the steering column, though.