Electrically Stumped IGN/Headlights

[RamJetFSJ]

OK, This one has me stumped. I have a RamJet 350 crate motor in a 80 Wag, which is a 2 wire hookup basically. Battery + and IGN. Ive got the IGN hooked up to the 10 Gauge Red with White Stripe under the hood, that originally went to the Coil + and the orig. Ignition Module Assy. Starts and starts at the Ignition switch. Runs/drives fine.

My problem arrises when I try to turn off the car, WHILE the headlights are on. The engine will continue to run, even with the key off, and removed from the ignition. As soon as I turn the headlights off (or even just to running lights), the engine shuts off.

The only thing I can figure is there is something backfeeding in the headlight switch possibly, but looking at my wiring diagram, I cant figure out how that would be possible. Im stumped on this one. Unless the PO did something weird up under the dash where i cant see, I cant figure out how this is possible. Anybody have any ideas?

[tgreese]

Is it wired as an '80 or a '73? Presuming it's wired as an '80.

The original wiring uses a resistance wire to prevent backfeeding from the alternator when switching off the ignition. Assuming this is a Delco 10SI or 12SI alternator? The headlights may not be backfeeding, but instead providing enough of a load that the alternator voltage is raised enough to backfeed. Try disconnecting the alternator plug excite wire when it's running on, and see if that makes the engine stop (don't cut it - it's nichrome wire and you can't solder it back together). You can substitute a diode for the resistance wire, and it will never backfeed again.

If it's wired like an '80, it's the brown wire #78 that goes to the bulkhead. On the cabin side of the bulkhead, it's a plain brown wire (not nichrome) which goes to splice J and then to the ignition switch.

[RamJetFSJ]

Wired like an 80 wag, but (to make things more complicated) with a GM one wire alternator. I definitely need to find that brown wire and make sure its not hooked up to anything.

The engine harness itself knows nothing of the rest of the wiring except "am I receiving IGN + on this one wire, and if so, I should run".

And to complicate things even more, I have a Painless H4 Headlight harness, so the Waggy harness is only supplying enough amperage to trigger the relays when the lights are turned on (not high load). I guess I should remove that from the equation and see if just turning on the light switch does the same thing.

[RamJetFSJ]

I checked and its a 10si alt. Not sure how to add a diode to a 1 wire alt, I didnt think they were needed. Bad Alt possibly?

[tgreese]

It's not an issue with the 1-wire alternator. The brown "excite" wire is not connected to the alternator. It should not be connected to anything.

Yes, it's possible your headlight harness is back-feeding to the ignition switch when the lights are on. You don't need a lot of extra connections to run headlight relays. I have headlight relays on my J20 and they use a single 10 ga feed from a circuit breaker on the fender, which is connected to the starter switch. Did painless give you a circuit diagram for the wiring harness?

[RamJetFSJ]

The painless harness is direct to battery, and then plugs right into the original headlight plug for the signal. Of course I installed it over 12 years ago, so I need to double check it all. Unfortunately it's all behind the grille. I'm not sure how it could be back feeding, but I'm definetaly going to look into it.

Confirmed brown excite wire not hooked up.

[RamJetFSJ]

Looking over the instructions for the H4 Headlight relay conversion, I dont see any way it could back feed into the Ignition. Also, when I turn the lights on with the engine off, it does not send power to the IGN + circuit that the motor uses, and I can tell since it doesn't fire off the fuel pumps like it does when you turn the Ignition on alone. So Im still stumped....

[az chip]

You have a crossed wire somewhere. Check the wiring on the ignition at the engine. Make sure there is no extra wires.

[RamJetFSJ]

Only other wire I can find is the IGN + supply to the electric fan relay. That all works as its supposed to, and I tried testing w/ the electric fan relay removed, with no change.

If the Headlights power supply and the Ignition + wires were crossed somewhere, then surely the headlights should come on with the Ignition, right? And vice versa, the ignition should come on when I turn on the lights. But it doesnt. Something is feeding power back into the IGN + (and not the ACC), only when the engine is already running, and the lights are on...

This may just be one of those gremlins I have to live with. It definitely makes it impossible to forget and leave your lights on!

[Stuka]

Do you use a relay for your headlights? If so, that could prevent them from turning on if the wires were crossed. Depending on where things may be crossed.

[RamJetFSJ]

The headlights are on a relay already using the Painless H4 Relay Conversion kit.

[az chip]

What I meant was you have an extra power wire feeding the ignition through the headlight wires.