you guys know the slp fan switch they sell for like 60 bucks? has anyone ever made there own by just getting a power wire and jumping it to the fan power wire with a switch in the cab or something like that? or is there more to it? im going to dig into some wiring diagrams that i have and see if its possible without blowing anything

 

Once the engine gets up to a certain temperature, the temperature sensor (the one near the water neck) completes a ground, trips the fan relay, and turns the fan on. Your sensor has two wires going to it, so while you're tracing diagrams, see which wire operates the fan. If you remove that wire from the sensor and touch it to ground, you should hear the relay click and the fan should go on. So, leave the sensor wire connected to the sensor. Then splice a separate wire to that sensor wire, run it through a switch, and the other side of the switch gets wired to ground. With the switch off, the fan operate like factory. With the switch on, you complete the ground and turn the fan on.

 

in my diagram the yellow wire comes right from the ecu onto the temp sensor and the black wire goes onto the auto trans temp, my car is a t56, there is no temp sensor,then the wire goes back to the powertrain control module, so is the black wire the wire i need to ground with my own switch?

 

Here you go: this address tells you what you need to know. I have a '95 z and used the OBD 1 instructions for this manual switch and it works just fine.
http://shbox.com/1/fan_sw_diagram2.jpg

Later

 

i have looked at that, so do i just need a on/off toggle switch and jump the high and low speed wires together? and use the resistors to trick the comp?

 

When I did this project I just connected the spliced in wires to a toggle switch that I installed below the cigarette lighter. Wires spliced into both the high and low fan circuits are soldered to one side of the switch and the other side goes to ground. The pcm works on ground; so, when you ground the circuits via the switch, both high and low fans come on. The connectors that you splice into are located on the passenger side inner fenderwell. Also, to route the wires into the passenger compartment you will have to remove the pcm, then route the wires through the rubber grommet that is just below the pcm on the firewall. Use something stiff such as a coat hanger wire and attach the splice wires to that and run them through the grommet. Once they are inside the passenger compartment you can easily route them to where you want to install the switch. This has nothing to do with manual or automatic transmission or temp sensors. It is simply a ground switch that activates both the high and low fan circuits. Hope this helps.

 

P.S. There are no resistors needed to accomplish this. You just make the splices as shown in the diagram at the link address I included in a previous post and then run then to a switch and then solder them as I mentioned. It would be a good idea to test the fans BEFORE you solder them. This can be done by simply grounding the wires against anything metal in your engine compartment. Additionally, you can find the splices at any radio shack. Just match them to the size of wire in the connector which, if I remember right is a #14 wire. Then use matching size wire to run to the switch. Also, you can use also use a lighted switch if you want. If you chose to install your lighted fan switch on your console I know that there is a power source underneath the console down near where the reverse/brake lockout switch is located, or you can get the power for the lighted switches from under the dash somewhere if you're going to install it in the dash.

 

Uhhh--my bad. It looks like you do have to use resistors on an OBD 2 setup vs an OBD 1 manual fan switch setup. I didn't have to do that with mine. I think you still wire it up as I mentioned but with the resistors in place as the diagram indicates--sorry 'bout that

 

well it will work without the resistors the comp will just throw a light

 

just wired it up, wired both hi and lo fan to the same wire and went to a switch then grounded it, no resistors, if i throws the cel light then i will put some resistors in front of the switch between the hi and lo wires, thanks man!!