Lt1 won't turn off "Help"

[Thekids68]

Hello, my son and I are building 68 nova with an lt1 in it and it won't shut off with the key . We are rookies at wiring sorry. The original car had a straight 6 in it . We took that out and put in a 95 Lt1 with the 4l60e. I used a FIC wiring harness with works separate from the car harness . I can't find a switched power source in run and crank at the ignition . What am I doing wrong? I have 3 old wires in the engine compartment I don't know what to do with ( purple /yellow/blue). These went to the old starter. Are those the problem ? Should those tie in to the lt1 starter ? Thanks

[avewhtboy]

LT1 is just like any other motor, I won't run with out feeding 12 volts to the coil so it sounds like your coil is not on a switched source.

[Thekids68]

The car starts and runs great . My problem is I cans get it to turn off when I turn the key off .

[minendrews68]

but, as the above post says, your coil could be set up to a "always hot" wire. It would start and run correctly, but wouldn't shut off. You will need to have a switched (hot wire that's hot when the ignition is on) wire to power the coil. That's where I would start looking too.

[Ron.in.SoCal]

I've seen this before. Was your ignition switch ever replaced/rewired?

[reschke18]

The purple wire goes from the ignition switch to the starter solenoid terminal labeled "s"
The blue wire is probably for the oil pressure gauge. Could possibly also be used in wiper circuit. Trace it out.
Trace out the yellow wire. It may have used to go from the starter to the coil for starting only ( now not used) or it may be for an electric speedo or wipers.

[reschke18]

At least that is common old GM color coding...

[Thekids68]

Ok thanks know I can start there

[MecHED]

Get a multi meter. Put black on the body of the car and check the positive terminal of the battery...if you read 12v then the connection of your black meter lead is adequate, if not make sure black in on bare metal either on the engine or body (it's supposed to work for both). Then place the red lead of the meter on the coil terminal and switch the key on and off. You should see voltage come in and out with the key. If it's hot all the time you have found your issue and can begin looking for a source that DOES come in and out with the key using the same methodology.

[shizzy]

Make sure the connector for the purple wire down on the starter hasn't rotated over and made contact with the Positive battery cable. I had a Cutlass that did that once.

[TheJDMan]

I have also seen a situation where the original ballast resistor has been bypassed/removed and the engine runs on with the key off. In that situation the alternator may be back feeding into the wiring harness. If that is the case you would need to install a diode in the alternator voltage sensing wire.

[MonzaRacer]

You probably need a diode in the key on feed from Alternator. A 400PIV should handle it well enough. place band on diode away from alternator plug. Generally what happens is there is enough power from regulator to keep car running as the key on wire runs through an idiot light to power, if alternator loses power it grounds the idiot light.
Also if you put diode in wrong just flip it, and remember to solder all connections. I personally crimp/solder/adhesive shrink tube all connections if possible.
Any questions, ask.
Lee

[no go nova]

What if the power source to the computer is not getting cut off? Because if its fuel injection it would shut off cause off no fuel from the injectors.

[no go nova]

I would check the key switch also to see if its killing the ignition power maybe your giving the computer 12 volts all the time. see if the fuse to the key on for the computer loses power with the key off.