Official Electric Fan wiring thread!

[lolcantturn]

Lols this just saved my thread, thanks man. I really needed a thread like this as "Fan wiring" searching titles on r3v only yields about 2 threads.

[giantkeeper]

Im tired of seeing all these threads on how do i wire my fan and people doing dumb stuff like wiring it on constantaly or using the snowflake button to turn it on method.

1: Install fan in car.
2: Find stock fan wiring on drivers side under drivers headlight
You should have red brown and black

Assuming youre using an aftermarket fan, you want to wire the +12 of the electric fan to RED and the ground to BROWN
Another method (in order to get the stock fan wirings' low speed to work) is to wire RED and BLACK together. But keep in mind because you have no fan resistor there wont really be a low speed as far as the fan is concerned. Another trick is to remove the fan resistor from the stock fan and wire it in series with the black wire.

3:Find the stock fan switch wiring: early model on drivers side, late on passenger side (1988 changeover)

Basically BK/BRN to GRN/BK will fire high speed
BK to GRN/BK will fire low speed

4: I always just utilize high speed and use this switch: (61-31-1-364-272-8 ) in series with an 80 deg C thermostat. Dont try to use the stock fan switch (2 or 3 pole) because most of the factory switches are setup to have the fan work as an AUX fan which you are no longer doing. You want the fan to turn on alot earlier than the stock switch has the fan setup

Ok, so I am good up to three (I combined the speed wires w/o resistor) - I'll have to verify my connections at the temp switch (which is 61318361787 Radiator/Auxiliary Fan Switch; 80/88C; Radiator Mounted with 3 Pin Connection).

Btw your PN does not appear to pull anything up.

Mine comes on when keyed, even though I set it up to run as above.

Thanks for posting this!

[NigelStu]

Thank you!

Now I don't have to sift through all of those other previously mentioned threads to get the correct info I need to wire my aux fan up to work!


Vote for sticky!!!

[328ijunkie]

Im tired of seeing all these threads on how do i wire my fan and people doing dumb stuff like wiring it on constantly or using the snowflake button to turn it on method.

1: Install fan in car. To Preface a GOOD WORKING factory fan will outcool most aftermarket ones. I run stock fans in almost all the swap cars i do here as they move ALOT of air.
2: Find stock fan wiring on drivers side under drivers headlight
You should have red brown and black (AFTER the Plug)
or BK/Blue BK/Green and Brown (BEFORE the plug)

Assuming youre using an aftermarket fan, you want to wire the +12 of the electric fan to RED and the ground to BROWN
Another method (in order to get the stock fan wirings' low speed to work) is to wire RED and BLACK together. But keep in mind because you have no fan resistor there wont really be a low speed as far as the fan is concerned. Another trick is to remove the fan resistor from the stock fan and wire it in series with the black wire.

3:Find the stock fan switch wiring: early model on drivers side, late on passenger side (1988 changeover)

Basically BK/BRN to GRN/BK will fire high speed
BK to GRN/BK will fire low speed

4: I always just utilize high speed and use this switch: (61-31-1-364-272-82 ) in series with an 80 deg C thermostat. Dont try to use the stock fan switch (2 or 3 pole) because most of the factory switches are setup to have the fan work as an AUX fan which you are no longer doing (STOCK FAN SWITCH IS 90/98C in most instances). You want the fan to turn on alot earlier than the stock switch has the fan setup
Pelican Link for switch
This will make the fan come on right under the halfway mark and making it so you never ever half to worry about pressing the snowflake or anything stupid like that. The car will cool itself just like its supposed to from the factory. Again this isnt the ONLY fan switch that will work. There is also a 3 pole 80/88C switch that you can use as well but you have to realize in stock form its setup to turn on low speed at 80C and high at 88C. If your fan isnt wired for this it wont work as well as i dont like that it waits till 88C to turn on high speed.

Picture for reference:


Some quick and dirty pictures of a S52E30M3 Car here.
Stock (nearly disintegrated) Fan Plug:





Fan Switch Wiring Modified. You can see the low speed trigger wire hanging out for reference:



Early Model Fan Plug:





Ive tried to collaborate everyones questions into a troubleshooting section:

NOW WHAT MY FAN DOESNT WORK!!! HELP!?!!?!:
First off
You need to make sure everything is present for this system to work. Unloader Relays must be present/functional. High/Low Speed Relays must be present/working and fuses 3,18, and 19 must all be in one piece. If only running High speed only the HIGH speed and unloader relays must be inplace/working and only fuses 19 and 18 are necessary:



-Fan doesnt turn on when car gets hot?
Short the two pins at the fan switch. Does the fan turn on?
YES: Engine isnt hot enough or cooling system not bled all the way. Is radiator burning hot all the way across? Can you touch the switch bare handed? You shouldnt be able to.
-Extremely Slim possibility is the fan switch is dead. This is where an IR thermo comes in handy, With the fan switch itself nearing ~83-85C the fan should trigger. In my experience it triggers at an external temp of <80C

NO: Check Fuse 19 (7.5 amp), Then Fuse 18 (30 amp). Both Good?
-If theyre both good, check for power at your new fancy fan switch. GN/BK should always have power with KEY ON. It is powered indirectly by the unloader relay.
-If there is power there with the key on, short the GN/BK and BK/BR fan switch wires and move on to the fan wiring. BK/BU (Pre Plug) or RD (Post Plug) Should have +12 at it with the fan switch jumped. If it does and the fan still doesnt work check for ground at the BR wire, if that checks out then your fan is dead.




-Fan is stuck on all the time
Verify that the fan switch wiring isnt shorted
Verify that with the car cool the BK/BR wire at the fan switch DOESNT have +12.
Smash your K6 relay a few times to make sure its not stuck.

Thats all i can think of :P


Member Klug added his setup:

Chiming in here with my modified electric fan setup.

Short story: I followed this DIY on how hook directly to the Aux fan wiring with a 80C switch. Easy to do, simple and not a lot of electrical cabling. I was running a SPAL 16'' Puller as my primary cooling fan for a few months.

This worked like a charm- except under the ONE scenario: If the temp switch kicks on the fan at 80C and starts cooling, and I was ready to park or turn off the car and the fan was still on- the fan would obviously lose power. IF I had to turn the car back on for whatever reason (maybe to move the car after you parked it) and the temp was still over 80C- the startup of the ignition I would blow the stock 30A aux fan fuse every time. I found out that this can happen when switching from the +12v of the battery (ignition ON but engine OFF) to the new +14.3v you get from turning over the engine and obtaining the power bump from running from the Alternator. By the way- I never blew the in-line fuse I added from the +12v of the fan- only the 30A fuse in the fusebox.

Also- which is a great point on why I modified it- was that say you are getting ready to pull into your destination, you might be idling a bit to find parking etc etc and the car gets up to 80C. The fan kicks on and might still be running when you turn the car off. Which is fine. But if you need to turn the car back on again, the thermo switch on the thermostat- which goes to the DME- will tell the DME that the engine coolant is too hot and don't supply fuel. So you get this hesitation when trying to start up. I can't get a definite temperature of what the thermostat DME switch reads that tells the engine that it is too hot. I only found out what resistance it reads at certain temps. If you know- I would really be interested what this threshold is.

Anyway- my plan was to remove the fan from the Aux wiring fuses/relay and run power directly to a new relay that has constant +12v w/o the ignition on. First tried to wire up a new relay and fuse to the stock fusebox. Wasted my time since I couldn't find the correct female blade inserts for the fusebox. Decided to do a completely standalone setup.

Here is what I used and how I wired it in:

Hella 30A Relay and weather proof wiring harness $15
- Relays are pretty much all the same from what I found. Went with this one since I decided on mounting it stand-alone from everything else and tried to make the install clean. Sure you can use a standard Autozone 30A relay, but finding the wiring harnesses are hard to find locally and at the end it will probably be a pretty messy wiring job. Installed mine on the side of the fuel pump relay cover.

30A In-Line fuse holders $4/each
- Used this instead of using the Accessory fuse holder (some have used this stock fuse holder for other things) Put one from the +12v Constant coming out of this stock fuse holder to terminal 30 on the relay. Used the other one for the +12v for the fan.

Here is my drawing and relay layout.

Relay Wiring
Terminal 30: +12v (12GA wire) constant from stock accessory fusebox (with In-line 30A fuse)
Terminal 85: Ground (12GA wire)
Terminal 86: Trigger switch (14/16GA wire) I'm using my 80C thermo switch with a manual override switch that I used a extra fog light switch and mounted it next to the defrost/hazards (to turn on the fan under 80C if needed) You need to tap into a 7.5 fuse that has constant +12v so fuses 21, 22 and 23 are always on. I tapped fuse 21 (NOT 10 as pictured) since it is used for other switches on the car. Run a wire from here, to the thermo switch. Then a second wire back to Terminal 86.
Terminal 87: Fan +12v (12GA wire) used an in-line fuse here to protect the fan. Mounted it near the fusebox for easy access.
Terminal 87A: NOT USED (unless you need power to something that is ALWAYS on and OFF when the fan is ON)

Notes:
Make sure you invest in good butt connectors, crimp (or solder if you prefer) and electrical wrap. I hate glossy electrical tape, so I purchased some premium wire wrap.

Thats about it! It's not the most complex job, but it gets it done and doesn't rely on anything stock. Hopefully this will help out people who might see the same issues. There are a few threads around that I've read about their fans blowing fuses left and right. This should be the solution. Good luck!!