I decided to write this up because i just did this mod today and could not find any how-to's on the net (that were not removed) so i had to figure out the relays and such on my own.

If you are using a basic switch, doing this mod will be very easy.

Basic Switch
Basically all you are doing is providing ground to a relay, which turns on the secondary fan.

Lighted Rocker Switch
If, like me, you want to use a lighted rocker switch, you will need to get a 12v relay. How the setup will work is like this:
-You turn on the switch
-The switch uses the 12v input to turn on the LED in the switch
-12v is sent to the relay, which then sends ground to the fan relay, turning it on.

Power Source
I would suggest getting your "hot in run 12v" power source from the accessory wires located in your console. For more information about these wires, check here: http://shbox.com/accy/Accessory.html
you will be using the pink wire. It provides power during power and run. It is important not to use an always-hot power source because if you forget to turn off the switch when you turn the car off, it will drain your battery.

Routing Wire Through Firewall To Relay Box
See this how-to: http://shbox.com/fw/Firewall_wire_feed.html
I routed the wires through the passenger side of the firewall, and then around the front of the car (by where the wash fluid reseviour is).

Test Relays
According to shobox.com, in late 94' and into 95' a new 3-relay setup was introduced. If your car does not use the 3 relay configuration, you will need to test the fan relay(s) to find which one to tap into. To test:
- Remove the top from your relay box
- Remove bottom from your relay box
- Put your key in the ignition and turn it over 2 clicks (just before it will start) so the car gets power
- Look inside relay box lid for diagram of relays. Look for relays that say "Fan #1" or similiar.
- Working with only 1 relay at a time, look from under the relay box and find the connectors for the relay you are testing. There will be a skinny green or blue wire; supply ground to this and listen for the fans to kick in (they are pretty loud so you cant easily miss the sound) When you hear the fan come on, you will need to release ground and hurry under the car to see which fan is on. I would reccomend using the secondary fan for the switch. (will most likely be #2 relay)

Origionally Posted on Z28.com by Scott (GradeZ28)

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