Use a single pole double throw switch:
L1----O
O---- Common
L2----O
Pull white wire off of radiator breaker and connect to L1. Crimp another wire onto blue wire connector of radiator fan switch and connect to L2. Common would be connected to white wire (12V) out of the radiator fuse (spliced between fuse and breaker). So when switch is up, circuit is "normal"; when down, you've jumped across the temp switch and apply 12V to the fan (fan on). This keeps all your fuses and breakers functional for safety.
|