mrobert

I turned the key to Lock , transmission in Park and the engine kept running.
The only way to shut the engine off is to shift into Reverse or Neutral. I am at a lost to figure it out.

Dynra Rockets

Is it actually running or is it "run-on" (self combustion from pre-ignition detonation)?

mrobert

No "run-on", actually running. If I have the key in lock position and I shift into Reverse or Neutral the engine will turn off.

DUB

The ONLY thing I can think of is that the ignition coil is still getting power even with the key off....and if my memory serves me correctly...you still have a points distributor...which means that the resistance wire that goes to the ignition coil also goes down to your starter and it can be touching the battery power wire.....thus...keeping your ignition alive and allowing your engine to keep running even though you turned the key off.

DUB

TimAT

I actually did that one time many, MANY years ago..

Barrist

Mine started doing the same thing a couple of weeks ago. (75 w/HEI)
I was thinking that it just wanted out of the garage.
I disconnected the two wire plug at the alternator, and it died.
Replacing the alternator soon, if it continues I will check back, and see what you found.

Have a Great Day,

Bill

mrobert

Just checked the wire that goes to the starter , can't see any problem .
But , yes , there is still voltage at the coil with the key in off/lock position.

mrobert

I just had the alternator checked out ... all good .
I guess I will have to begin tracing wires, can't give up and fix a kill switch.
I have had this car for 41 years and have kept it all original.

CanadaGrant

I'm not much on electrics but if your coil is still powered with the ignition switch off it either has to be coming from the starter to coil bypass wire that supplies a full 12 volts during start or the ignition switch itself. I know you checked the starter to coil bypass wire but try disconnecting it from the outside terminal on the starter, then start the car and then see if your problem goes away. It could be in the starter solenoid. If not the ignition switch is my guess....

Peterbuilt

'It turns off in reverse or neutral'.
How can that be?
I have to stick around as this is interesting.

DUB

Knowing that you still have battery voltage at the coil when the key is turned off....I still might remove the wire on your solenoid that goes to the coil. And then see if it goes away.

I completely missed that Pete.

I have to wait for more clarification on this due to it makes no sense...unless someone has played around with the wiring.

DUB

TimAT

Is it possible the park interlock cable is keeping the key from going all the way to OFF/LOCK? That could be why the coil is powered when the key is OFF?

Peterbuilt

Hi again mrobert,
1974 has a 'seatbelt/starter interlock, does yours work?
Do you have to buckle up before the car will start?
Pete.

joewill

if you have full time power to your coil even with the switch off then you should be suffering from a dead battery pretty often as this will drain your battery.

7T1vette

Not sure how coil can be powered with the ignition in OFF position. It would have to be getting 12 vdc from some other source, unless the ignition switch was defective.

midigike

I have heard of this before, car kept running on after shutoff and the ignition switch was the culprit. Broke internally was a 1969 model though

mrobert

I removed the outside wire on the starter solenoid, started the motor turned the key to OFF ... motor kept running, had to pull coil wire.

The first thing I did was get a new ignition switch, no help. Next, I got a new key/lock cylinder, no help. Never had to have the seat belts connected to start the car, but I tried ... still won't stop running in Park.

Forgot to add one thing... no more voltage at coil with key in lock/off and trans in park position . Still have to pull coil wire.

Must be in the wiring somewhere, I can't / won't give up. It is embarrassing
to have a Corvette that doesn't perform correctly.

Forgot to add one thing... no more voltage at coil with key in lock/off and trans in park position

CanadaGrant

The only other thing I can think of is do you have a wire plugged into the IGN terminal on the under dash fuse box that might be supplying 12v to the coil? Also, is there any other wire running to the positive side of the coil besides the one terminal holding the two ignition wires? Did you also check the ignition switch connector wire terminals?

Peterbuilt

If you have no voltage at the coil positive then how car your car still run?
Are you testing between the coil + and ground?

Interesting about the seat belt interlock.
Seems like yours was bypassed previously.
Related to the new problem?

7T1vette

You can have a condition called "engine run-on" or "dieseling" where the engine can continue to run (poorly) without an ignition source. Essentially, there are some carbon deposits in the combustion chamber that stay hot enough to [barely] fire the air/fuel charge, once it is fully compressed at TDC. This was a common problem when engine timing was significantly retarded for emissions purposes. Car makers came up with 'creative' approaches to put a load on the engine so that it would shut down (not enough power generated when dieseling to overcome the applied load). For example: If the car had A/C, the compressor may have been engaged for a few seconds after the ignition was turned to OFF.

"Dieseling" is easily differentiated from a normal running engine, as it runs very poorly with spotty ignition firings, etc.

If the engine is running normally, power is getting to the ignition system somehow.