Quick question guys...I think it should be an easy one.

I am wiring up a fan relay and a fuel pump relay on my 69 Roadrunner. I'm not a total idiot, but was wondering if I could hook up the "ignition" wire from the relays (so the fuel pump comes on with the key, and the fan kicks on when it gets up to temp) to the positive side of the coil...I am not very familiar with MOPAR ignition systems, and don't know if MOPAR drops the voltage at the coil or not. Does the voltage stay a constant +12VDC (give or take) on the positive side of the coil whether you're starting the car and/or once it's running?

If this will NOT work, where is an easy way to get ignition voltage when the key is turned to start/on.

Thank-You!!!

 

First question is, "what do have" for an ignition system?

If you have the original points, or converted to Mopar breakerless, the switched igniton, or "ignition run" comes out of the bulkhead, goes to one end of the ballast resistor, and branches off to feed the voltage regulator.

You do NOT want to tap off the coil + terminal. ALL U.S. built cars back in those days used a coil resistor. Ford/ GM used a resistor which was in the harness, Mopar used the ceramic ballast on the firewall

If you have the original ballast wiring (points) there should be two wires into each connector at the ballast. One end has blue and brown, which you do NOT want

Other end is two blue wires, which is what you tap into