So you are saying as long as the engine is not running you can turn the ignition switch On and Off continuously and there is 12 volts at the coil fuse when the ignition is On and zero volts when the ignition is Off which is normal.

If you start the engine and turn the ignition Off the 12 volts at the coil fuse goes to zero volts then the voltage increases to keep the engine running for a couple of seconds but eventually the voltage goes to zero volts and the engine shuts Off?

Verify the ignition switch Accessories position works.
Close the doors.
Turn the ignition On.
Turn the radio On.
Turn the ignition Off.
The radio should continue to work.
Open the drivers door.
The radio should shut Off.
Close the drivers door.
Turn the ignition switch to the Accessories position.
The radio should work.

If not the ignition switch needs to be adjusted.

 

Did I read that this was a replacement switch? At the factory we had very few highly trained people that worked on steering columns. They came in assembled and were well known PITA. Had very few that came in bad but even new parts can be bad.

 

You are spot on about the first part. 0 Volts when ignition switch is OFF, and 12V when ignition switch is ON.

The second part is kinda tricky though. This is what I did. I start the engine and turn the ignition off, but the engine keeps running. I go to the fuse box and remove the coil fuse (because the fuse is essentially 0 ohms, theres no voltage across it, so I have to remove it to check the voltage) the engine shuts off, which is normal, an open ignition coil circuit should shut it off. When I check the voltage at the two terminals where the coil fuse was immediately after I remove it, it slowly goes down from 12V to 0V, which tells me that there was still 12V there when the engine is running and I turn off the ignition switch.

Incidentally, when I turn the ignition off with the engine running, it sounds like it is shutting off, then revs right back up. Today, I left it running with the ignition off for a while as I was doing this, and the engine did this several more times. One time, it actually shut off, but I wasn't able to replicate this. Maybe this is actually what you are describing? The voltage going to 0 then back up to 12, and repeating?

I'm not sure I explained that very well, so please let me know if I need to clarify something.

Hmm maybe. I'm not known to be the luckiest person alive haha. I wish I could bench test the ignition switch... Is there information available that says which pins should be open/closed at each switch position? I'm planning to get a proper FSM, but I doubt it would have that info.

 

Now that you mention it, the delayed accessory bus doesn't work. The accessories position works fine though, so I thought that was because of a bad relay or timer or something.

Anyhow I'll take off the ignition switch and remount it tomorrow. Maybe it'll fix the problem *fingers crossed*

 

Try this first.

You may have excessive play in the steering column tilt mechanism.
Physically move the steering wheel up and down.
Physically move the steering wheel side to side.
There will be some play but too much play can cause a problem like what you are experiencing.

Position/tilt the steering wheel to the center position and see if that cures the problem.
If not tilt the steering wheel all the way up and see if that cures the problem.
If not tilt the steering wheel all the way down.

You don't need to remove the ignition switch to adjust it. Just loosen the nut and bolt and move the switch up or down the column.

If you remove the nut and bolt to change the ignition switch make sure you tape the rod that activates the hi lo beam switch to the steering column. It just lays against the column. If it falls out of position you will kick yourself in the azz.

Yellow arrow in the picture points to the hi lo beam rod that you want to make sure does not fall out of position.

 

Lol ... I bet I know how you learned that lesson ...

 

Hey guys, it's me again.

School's back in so I don't have much time to work on this thing now... I did try remounting the switch but no change.

But in the meantime I've managed to hack together an aldl cable and read the DTC codes... got a 42 which apparently means shorted or grounded ignition control circuit.

How do I check this out?? Where is this ignition control circuit? What does it refer to in a 93 corvette?

Thanks in advance,
Ted

 

To pull codes you take a piece of wire and connect pin A to pin G on the diagnostic connector and turn the ignition On. Any codes will be displayed on the dash cluster LCD.

42 is probably a bogus DTC. Could be an old code set if you messed with the ignition coil or ICM wiring.

To clear the code disconnect the negative battery cable for a couple of seconds and see if it resets.

You have a problem with the ignition switch circuit because the engine keeps running with the ignition switch in the Off position. There should be no voltage to the coil fuse which provides power for the coil and the Ignition Control Module with the switch in the Off position.

If the DTC was for real the manual says the injectors are disabled when DTC 42 is set.

 

Did you figure this out? I just bought a project c4 and have the same issue that is solved by messing with the tilt and turning the ignition off. I was a bit scared at first that I would have to stall the engine since mine is a stick but luckily it did turn off. I have a feeling it is the ignition switch since I believe it to be original.

Thanks!