my 74 won't shut off when i turn the it off and pull out the key. It's quite disturbing when i have to get out and pull the coil wire off of the coil, any ideas on what it could be, i was thinking it's probly the ignition switch where they key goes in. Thanks for any help.

I was looking for my wiring schematic to reference, but to the best of my knowledge, the ignition switch should be the problem. I ordered a new ignition set from one of the corvette on line stores. This should fix your issue.

This could actually be an alternator related problem. The ignition supplies power to the alternator internal regulator when you turn on the key. Usually this is a brown or white wire. It is in the two wire plug going into the alternator from the side. (the red wire going to this plug is hot all the time, as is the battery terminal on the back of the alternator) This ignition wire activates the regulator. Once the car is running this becomes a power supply. If this supply is not limited, the power will feed the ignition system by going backwards through the wiring. Disconnect the two wire connector from the alternator then start and shut off the car. If it shuts off right away, this is your problem.
Limiting the current is not part of the alternator or regulator. There is a resistor in line going from the ignition switch to the alternator. This resistor on some cars is the "ALT" light bulb itself. Some use a bulb and a resistor, in case the bulb burns out the car will still charge. A volt gauge does not have to be part of this circuit. All it does is monitor system voltage, which it can do from several points. Amp gages connect to the battery lead on the alternator, so it's not part of this picture either. I don't know where the resistor is located in our C3s, I would need to look at a wiring diagram. Often it can be found in the dash cluster. If you are looking for a short term fix so you can drive for now, connect a 194 or 168 light bulb in line in this wire to the alternator. You may want to use jumpers so you don't cut the wire. You will also have to install a jumper or the other wire to the plug. Put the bulb in a socket with wires and hook it in series. The bulb will acutally operate as a "ALT" light. When you turn the key on, the bulb will have power on the ignition side and light up. When you start the car the alt will start charging and you will now have power on both sides, so the bulb goes out, unless the alternator fails. When you shut the car off, the resistance from the bulb stops enough amperage feedback, so the car will shut off. With the alternator not turning, there is no longer any power, and the entire system shuts down, leaving the bulb off, and no power flow.

The bulb is a temporary repair. Although a friend of mine left his Olds wagon this way for several years instead of getting into the dash and repairing the resistor. There can be other causes, but this is the most likely, and the most common. Let me know what happens, and I may be able to help more.

Ken Styer

hello, sounds complicated and maybe helpful, however, it did this a couple times last summer but then stopped, then a couple weeks ago my alternator stopped charging and i took it into napa to get it tested, sure enough it was toast, i bought a rebuilt alternator and it charges perfectly, the not turning off situation did not start as soon as i put the new alternator on so that leads me to believe that it is not the alternator. Any other suggestions would be great

Reread my post. It's not the alternator. But it could be lack of resistance in the wiring to the alternator. (this is not the only thing that only be wrong) If this still sounds confusing let me know, and I will try to clear it up.

i guess i'll start with unhooking the two wire connection on the alternator????

Yes. If it shuts off, we'll go from there. If not, it's a different problem.

Ken Styer

I know this is an old post, however... I don't see the problem.... Why stop driving?

really the only reason i ever stop driving is because 1. people want to gawk at it, 2. i run out of gas money quickly at 8 miles to the gallon

Lets hear it for the less than 10 MPG crew I have a small block and get around 10 most of the time, I keep pondering why, , can't have anything to do with my driving style , like I care

Ok, I believe I had the same problem with a blazer I had, freaked me right out. I pulled in the driveway after a night out, turned the key off, trucks still running, crawled up into the engine compartment, pulled the "hot" wire off the distrubtor and the damn thing still kept running. I finally pulled the ground wire off the battery and it quit. What I did was install a ground strap from the engine to the frame, never happened again. Beats me

Dave
Mr69vett