Need help with electrical gremlin

Hey guys, I’ve built a 65 beetle with a 6.0 ls up front. The car has about 600 miles on it and all the sudden now when I turn the key off the car keeps running for maybe 10 seconds. It does this about 75 percent of the time. I’m using a universal painless harness and an ignition switch from a 68 camaro. Any ideas what would cause this? Ignition switch going bad?(it was new)
Also one other thing. Sometimes when putting on the left turn signal the horn will honk and send a little shock through the lever. Would this have to be a ground issue or could it be something else? Thanks

Sounds like horn wire has an intermittent short to the turn signal lever.

Don

So a stand alone LS harness... GMPP or aftermarket?
What other circuits are wired to the run position of the ignition switch?
Have test light or voltmeter? Probe ignition position at switch. Start vehicle, shut off. Does light fade away?, or voltmeter decrease slowly from say 13-14 volts?
Remove ignition powered fuses one at a time. See if the light shut off instantly, or meter goes to zero.

It’s just a universal painless car harness with a FItech ultimate ls setup. When I turn the key off it doesn’t just sputter, it keeps running and I can rev it just like I never turned it off. It shuts off in about 7-10 seconds after turning it off every time. I’ll try to do some checking like you said. Thanks

Every EFI system has to have some method to command it to turn the engine off.

Probe that wire with a voltmeter/test light with the engine running. Turn the key off. Does the voltage stay high, or does it go to zero? If it stays high, it's likely a problem with a switch or short somewhere in the chassis wiring. If the voltage goes to zero and the engine keeps running, it's something in the EFI system.

Thanks

This might not apply to your Camaro ignition switch but I am installing a Painless harness in my 65 gto with a 6.0 l76 and painless needs to tweak their instructions a little bit. When wiring my ignition switch I emailed the tech support and they replied telling my this info ,that isn’t mentioned anywhere in the instruction manual.
#1 ignition switch terminal that has #931 wire needs a jumper wire that goes to ignition switch terminal #2. This splice is in a factory harness but since my Painless harness is made for multiple vehicles that may not need this splice they have you use a jumper wire.Would be nice if that little piece of information was in the instructions don’t you think.This might apply to you or it may not but I think you should find out directly from them.

I’ll check into that. Thanks

We’ll I figured out what was causing the run on problem. A few weeks ago I added a rear mounted trans cooler with a fan. That fan is the problem. I have it wired directly to the fuse box in one of the extra spots on the electric fan circuit. I’ve also tried the horn and accessories circuits. It runs on in all of them. If I unplug it, it shuts right down. How can I solve this problem without installing a manual switch for it?

Quote:

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Originally Posted by ragtop1968rs

We’ll I figured out what was causing the run on problem. A few weeks ago I added a rear mounted trans cooler with a fan. That fan is the problem. I have it wired directly to the fuse box in one of the extra spots on the electric fan circuit. I’ve also tried the horn and accessories circuits. It runs on in all of them. If I unplug it, it shuts right down. How can I solve this problem without installing a manual switch for it?

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What is probably happening is the fan is backfeeding into the electrical system and I can think of two ways to correct it. One is with diodes but with these they are basically one way valves and they do have a voltage drop across them to where if you have 14.4 volts going out of the wire to the fans, once it passes through the diode the voltage may be down a volt or so which means the fan spins slower than at the higher voltage.

The other way is with a relay with the main power for the relay and then to the fan now on a battery circuit and then the relay gets switched on and off by the ignition switch.

Personally, I would go with the relay design.

Jim

Use a Schottky diode. The voltage drop will be less than a volt, probably a few hundred millivolts depending on the current and diode.

Don

Do you know what size diode I would need? Fan is a 10” 650cfm and draws 5.3 amps. Thanks

These should be ok:

https://www.ebay.com/itm/25395124384...sAAOSw4c5b0zZJ

Don

Great, thanks for your help.

Hey Don, probably a dumb question but does the diode just splice into the line running from the fuse box to the fan? That’s what I did and now the fan doesn’t come on at all. Thanks

Never mind, I had it in backwards. Works now.