just some pics of the fan override switch by Wild Weasel:

diodes and resistors assembled:



testing resistor:



underneath the fuseblock:



diode in place:



resistor in place:



where the switch will eventually be mounted:



overall very easy to do, and does what its supposed to do. I have a bunch of leftover diodes if anyone wishes to do this in the future

It seems that just a simple hookup to the blue wire (tying into the wire) going to the fan itself with a spst switch going to a 12volt source would eliminate all of the diodes and resistors.
This is how I've always hooked up my fan override switches in all cars I've owned and never had a problem with it.
Also, the blue wire should be coming off of pin 87 of the fan relay which is only switched on when the PCM tells it to. Another words, hooking to the blue wire basically goes to nothing on the relay and still lets the PCM tell the relay to switch with 12volts going to the fan when needed.
It has it's benefits as the led letting me know the fan is on is on when I turn on the override switch or when I forget about it and see it on because the PCM decided to cool the engine or the A/C is on.

Just some food for thought and a simpler way of looking at the setup.
Oh, the blue wire is for the '95-99 J-bodies but wouldn't see why it wouldn't apply to the newer cars too.

Misnblu



Misnblu.com
Newbie member since 1999
Thank you Dave and JBO!

Wild Weasels method uses the existant power source, so you dont have to worry about fusing anything. All your doing is providing a ground for the relay to turn on the fan. The diode isn't necessarily necessary, but is in there as a safety.