d.i.y.s. fan switch...

[Brett Garret]

I keep hearing its cheap and easy to build your own manual fan switch for like $9 at a Radio Shack. All I wanna know is what do I need and where I find so instructions? Thanks guys :cool:

[98Camaro3.8]

http://web.nmsu.edu/~shanemar/camaro...fanswitch.html
;)

Matt

[Wicked 3800 V6]

That's EXACTLY what I used, except I had LEDs with the resistor built in, and with a screw-in-cover on them already.
-Rob

[Brett Garret]

I need something REALLY in detail. I have the parts but i need something thats like an explanation to an idiot. Thanx for the help.

[98Camaro3.8]

No offense, but if that is too deep for you, you should probably have someone else do it. That is about as simple an explanation as there is. :(

Matt

[Brian Dieckman]

Even better: use 1 dual-color LED and attach it the same way. Red when low, Orange when high! The resistor values should be the same.

-Brian

[Brett Garret]

Ok, Im trying to do this on a 3.4 and im having trouble finding the connecter to tap into.

[Backfire]

The 3.4L setup is different than the 3.8L. THere is only one fan and one relay. If you look in your manual, you can find which relay is connected to the fan. I believe there is a small gauge green wire that can be tapped into to contol the relay from a switch. You either need to ground the wire or connect to 12V. I will check and get back to you.

[Backfire]

The relay is at position D in the engine fuse box. There are 4 wires connected to it. The two larger gauge wires on terminal 30 and 87 are the power wires for the fan. The other two, smaller gauge wires are the control wires for the relay. The brown wire on terminal 86 is 12+ when the ignition is on. The green wire on terminal 85 goes to the pcm. When the fans need to be turned on, the pcm grounds the green wire. The manual fan switch is used to perform this task. You need to run a wire from the 85 terminal/green wire to a switch inside the car. One terminal on the switch is connected to that wire. The other one is connected to a ground. When you throw the switch, terminal 85 will be grounded, which closes the relay, and the fan comes on. It you are hooking up an LED, you could wire it inline with the ground wire from the switch. It won't tell you when the pcm turns on the fans but it will tell you when you have manually.

Check you wiring and all the polarities in case I made a mistake. That way you won't blow any fuses :eek: I just tried it by using a spare piece of wire to ground the green wire terminal on the relay and it worked. Just double check for safety!

Here is a quick picture of what I mean. The blue lines are the relay terminal. The red circles the new wiring you need to do. You may be able to find the green wire over by the PCM and tap into it there. Just use a voltmeter to test it first.3.4L Fan Switch

If any one sees any problems with this setup please let me know, as I plan to add this soon as well.

[ April 25, 2002: Message edited by: Backfire ]</p>

[Brett Garret]

THANX A TON. Unfortunatly Im not very inclinded to diagrams but Im gonna go piddle with it and see what I cant come up with. Ill let u know how it goes. Also Im sure the other 3.4s here appreciate it. Thanks again.

[Backfire]

You CAN tap into it over by the PCM. On the connector attached to the side of the pcm, Terminal J is the wire connected to terminal 85 of the fan relay. Be careful cause there are three green wires in that connector. But you could tap in there so you don't have to run wires across the engine bay to the fuse box

[LVGreenBeast]

So... since there is only one wire to run, i'm guessing the 3.4 fan only has on/off not high/off/low speeds right?

Also, if the above is true, does that one wire light the led's and act as the power for the switch or do you have to find another lead for the led/light?

[Backfire]

Well, I setup the switch this afternoon after I posted. I did tap into the wire by the PCM. I pulled back the wire loom and made the connection. Once back together you cannot even see it. I ran the new wire to a switch.

I didn't put a light in. But, to do so, you could run an LED inline with the switch. Either before or after the switch should work. The one issue with that is the extra draw on the 12V source for the relay control. I don't know what it is capable of supplying. I doubt the LED will cause a problem but it is worth mentioning. I will probably try that setup first.

There is only one setting on the 3.4L fan as far as I'm aware. There is only one relay so I don't know how you would control speeds.

[LVGreenBeast]

Cool, thanks... did you run a resistor between the pcm wire and the switch?

[Brett Garret]

Nice, I tried to this afternoon and ran into one prob. I have currently 2 diff color wires&lt;black,red&gt;, switch, blue led, 470ohm resistor. I ran the wire to the correct port behind the fuse (didnt tap so to speak)&lt;red wire&gt;. When i grounded it, the fan turned on. Also when i ran the other wire from the ground to the other wire&lt;black wire&gt; it ran. Then i ran the black one to the resistor and LED then the switch. Then attached the red just to the switch. The LED lights but it shouldnt, and it also wont run. When i touch the red to the LED (bypassing the switch) it lights and runs. Im thinking its something around the switch. Let me know what you think. So simple yet so difficult [img]graemlins/rofl.gif[/img]