yea my key was stick at times to way before the no power to trans. just sayin the key switchs on these thing make them do alot of wierd stuff.

 

The key isn't actually stuck. I can take it out while it's in the cylinder and then turn the cylinder to start the truck. The problem I'm having is that the cylinder won't go back to the OFF position. I've searched the forums and haven't found any information about how to diagnose the problem. I'd really like to figure out what's going on before I start replacing parts at random.

My first suspicion is the shift interlock but I haven't found any information about that system or how it works. I went to the library and looked on their Mitchell OnDemand system but it didn't have any troubleshooting information about it.

 

Let's see diagnose, take an x-ray of the column, send to General PO Box GM, Detroit Mich.

 

my truck was doing the same thing. there is alil crome button rite under the key . its bolts to the electrial part of the key switch. push in on the button while rockin the key back to off. if this works for u then the electrail part of the ingtion switch is bad. u will need a ac delco switch. to fix it.

 

Thanks! That's exactly the kind of information I was looking for. I'll check that out in the next couple days. Tomorrow I'm taking my nephew up to Mt. St. Helens in the old '93 Jimmy.

 

More information: I discovered that when the key turns back to the full OFF position there's an audible click just before when I put the shift lever in park. That suggests to me that the solenoid in the steering column isn't letting the cylinder return to the OFF position. Since it seems to be connected the shift lever I'm suspecting the neutral safety switch. Is there a way to test that?

 

I'm a proffesional mechanic, and had a real headscratcher with this same problem last week on a 2003 blazer xtreme, there really isn't any information out there on the floor shift models, according to alldata and mitchell this truck was only offered in column shift.

remove your lower column shroud there's 2 screws and it should just pop off, you'll see just behind the key cylinder there is a big white solenoid with a gold button on the bottom of it, that is your btsi solenoid. (brake transmission shift interlock) it should have a dark green with white stripe wire going to it and a black wire. put the key in and turn it on, the button should pop up, and as long as you are in park and your foot is off the brake it should stay up, try stepping on the brake, whenever your brake lights are on the button should drop. try turning the truck off normally and taking the key out, if the button drops before you get the key all the way out, usually at the off position, then remove your center console and on the side of the shifter there is a little solenoid that acts the same as the solenoid on the column with the gold button on it, step on the brake with the key on and see if it moves, if it's sticky or if it doesn't move then you need the solenoid, not cheap.. my cost was around $200, it comes as the whole shifter assembly, but was the fix for this truck.

the btsi solenoid is designed to be only energized when the shifter is in park and your foot is not on the brake, but after time the switch in the shifter wears out and the system doesn't "know" you are in park and won't let the key out.

alternatively on this truck and on my 02 zr2 there is a little "knockout" directly under the solenoid, you can remove the knockout and stick something... like a small screwdriver... in the whole and manually push the button to let you rotate the key to lock and remove it

also you said you were able to remove the key without it being in lock and were still able to turn the cylinder, in that case, yes, you do need a lock cylinder to cure that.

the whole point of the btsi system is to make sure you put the truck in park before you remove the key and walk away from it, this way the truck will still be where you left it when you come back and it won't wander off.

 

Thanks! That's some awesome information. I won't be able to do anything more with the Jimmy until early next week as I have gigs all weekend. Sometimes making money gets in the way of working on my various S- and T-series trucks and SUVs but then again playing gigs gives me the money to work on the trucks.

 

UPDATE: I haven't been back to work on my '98 Jimmy for a few weeks because my '93 needed some work. I replaced the fan clutch, water pump, fuel pump, sender, front pads and rotors. Then I had some gigs to play. After all, playing music pays for the trucks.

Today I went back to work on the '98. I did some more research about the system that locks and unlocks the ignition cylinder. There's an "automatic transmission controller" attached to the floor shifter. It sends the signal to the brake transmission shift interlock solenoid (BTSI). I took the top off the floor shifter console and checked it out. The ATC has a pin that retracts to allow the shifter to move out of park. That pin wasn't always retracting or returning. I moved the shifter back and forth several times until the pin started functioning properly.

I tested out the key in the lock cylinder and it worked every single time. I tested it about twenty times over the course of a couple hours and every time I shifted into gear and back to park the key turned off and returned to the lock position.

Until there's another major malfunction I'm declaring this problem fixed. In the meantime, I started working on the HVAC issues and discovered a lot of mold on the hush panels under the dash which makes me think this thing got wet inside at some time.

 

...and today it malfunctioned every single time. I'll have to go back to more testing and diagnosis in the morning.