I thought I should asked before I go and design a relay system. I have the following wires for my fan. Wiring harness 152 151 157 and ground. The fan has two wires + and -. Plus I have two wires from the computer. One turns on a fan at 180 deg and the second wire will turn on a fan at 220 deg. These wires will be connected to relays. I am only using one large fan from summit racing. So I will only need to use one of the fan wires.
I would like to be able to have the computer regulate the fan plus be able to override the computer with the switch on the dash.
I was thinking of using the computer to control the fan as if it were an air conditioning switch. But which wire would that be. Or am I missing something at the end of the front main harness.
Doug, I'm not sure about the computer hookup. What type of signal does the wire send? Ground or hot. You would also need to know what the turnoff temp would be. On at 180, off at ?.
To hookup the fan through a relay you can buy a standard horn relay and follow the connections as described. All universal relays use the same numbering system.
# 87 to Battery + or circuit breaker on firewall.
# 86 to temp sender on engine (fan sender)
# 85 to wire 151 from Classic harness
# 30 to fan +
Ground the other wire to the fan to the chassis.
To use an over ride switch attach wire 157 from the Classic harness to # 86 on the relay. The fan over ride switch on the dash has wire 157 and 161. Remove wire 161 and attach a ground wire to that terminal.
The temp sender is supplying the ground for the relay. When it gets to the stated temp it grounds itself. That's why you run wire 157 to the same terminal on the relay and supply a ground at the switch. When you flip the switch on you supply a ground to the relay which turns the fan on.
Don
Fan connections for CR with computer control
Linear Mode
