Greetings, I am attemptingto wire in a 12vdc fan to my radiator. Either the pink ign. wire or the red/blue start wire needs to be wired HOT. Any ideas? This is a 1968 Cougar. Oh, how I wished that we kept our 67 Cougar, when we bought it new back then! Quick connection<bltfrspd@aol.com
Sounds like you need a power source that is hot with the engine running. Pink wire will not deliver the 12 volts you need.
Something from the voltage regulator or nearer the ignition switch.
You might be able to use the pink resistor wire or wire to the coil as a trigger for a relay from the battery to power your fan. Use a quality relay with a 30-40 amp rating.
By all means use a relay when powering the fan.
Steven
Yes, cheap easy insurance against premature switch failure and over-current on existing circuits. However, you should use inline fuses as you will be bypassing the fuse box on this one. I generally put a 15 amp on the relay control line and a 30 amp on the supply
Here is a typical wiring:
Run a 12ga wire from the ‘S’ terminal on the alternator to the RELAY 86 pin (with a 15amp inline fuse) and then run a 12ga wire from the RELAY 85 pin to ground. This is the switching voltage, active during ignition (control line). The relay is now fuse protected against internal shorting.
Then run a 10ga wire from the left side of the starter relay (BATT +) to the RELAY 30 terminal (with 30amp inline fuse), and last run a 10ga wire from RELAY 87 terminal to the positive fan lead. This is the switched voltage (output supply), and is now fuse protected against shorting via the fan.
Solder and shrink wrap all connections, have fun!