early e30 electric fan wiring

[E36M3LX]

i have an 86 325es with an obd1 m52 and i cannot get the electric fan to turn on. the car overheats after idling for about ten minutes. i am running a z3m rad with a 2000cfm spal pusher fan, brand new low temp fan switch and low temp thermostat. i really suck at wiring so im pretty sure this my problem here lol

here is a picture of the wiring ive found on the drivers side


can anyone tell me which two wires out of these five go to the the fan temp switch on the side of the radiator? i want to use high speed only. the two wires on the left are green/black and black, the three wires on the right are black/brown and black/green(2).

also, can anyone confirm that i have the fan wired right?


im using the red wire for power and brown for ground. there's one more wire that i have cut and is not connected, it is the black wire shown in the picture. should that be connected with power or ground?

[mcdougal]

Subscribed as I have the exact same car and question.


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[E36M3LX]

THIS THREAD has helped me quite a bit, but it doesn't show very much about the early e30 wiring, nor does it show how an aftermarket fan should be wired.

i've found this on another thread


looks like early e30 uses two temp sensors in the radiator. so those five wires i posted earlier are the right ones but which of the five do i use?

and this is what the stock wiring looks like for the aux fan on early e30


it appears that three wires are being used; black, red and brown(which is barely visible) and im only using red and brown. not sure if the black needs to be connected to ground or power. my guess would be connect it with the power wire but i dont want to try it and burn up the wiring harness.

please help! someone on here has to have been through this before. thanks in advance

[E36M3LX]

Bumpin it up! Anyone have an early e30 with electric fan conversion?

[pandaboo911]

early e30 electric fan wiring

Yup.
83 318i here with a 16" SPAL pusher.

I used the simplest method which is to wire the low and high speed together at the fan plug. This means you will not use a fan resistor and the fan will run on high speed on both settings.

My e30 came with one 3-prong fan switch. Located on the drivers side. I had to extend the wiring to the passenger side.
I converted to a 2 prong fan switch that triggers at 88C for low and 92 for high.
Anything colder and you're losing horsepower (stock e36 is 92/99C)
I did this shit along time ago so I apologize for not remembering wire colors.

Find out which wires are low/high speed on the fan side (I think black and brown but please double check) and wire them together to your fan's ground.
Then play with your fan switch wires and see which ones trigger the fan. 2 of the 3 wires on the 3 wire bundle should trigger the fan because there is a low and high speed. You can get a 2 prong fan switch because your fan is running on high anyway.

So to clarify there are only 2 steps.
1. Wire low and high speed together black/brown (most e36 guys do this)
2. Extend fan switch wiring to passenger side and connect with 2 wires that trigger fan.

Small note: although my car was wired correctly, the fan did not trigger and nearly overheated at idle. You need to make sure your radiator is completely bled. The fan switch is in a shitty location where an air pocket can form.

I can further help if you tell me what fan switch you are using

[_Keith_]

I took my 87 left a 3 prong fan switch in as I'm obd1 now and just wired the red wire off the plug side on the driver side to fan power and the brown to the ground. Capped the other (low temp fan switch)

Everything works fine.

[E36M3LX]

alright guys, thanks for the replies.

i still can not get the fan to come on

this is the temp sensor i am using


this is the wiring for the temp sensor. i did the two green/black wires together and the black/brown wire by itself


and this is the wiring for the fan. black and brown wires for ground and red for power

[_Keith_]

You really don't need to run them in series. Take the black wire off the fan plug it's not a ground! Brown is ground


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[E36M3LX]

You really don't need to run them in series. Take the black wire off the fan plug it's not a ground! Brown is ground


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i will take the black wire off, thanks for that. i noticed that the radiator does not get hot, especially the temp sensor, but both hoses get hot. im thinking this might be a sign of an air pocket.

unfortunately, with this being a swapped car there is no bleed screw/bolt. does anyone have any tips/tricks to bleeding a motor swapped e30? ive read that its a self bleeding system, but that's hard to believe.

[328ijunkie]

Your fuse is now blown :(.

[E36M3LX]

Your fuse is now blown :(.

cant you be a little more helpful than this? You seem to have the majority of the knowledge here on swapped e30s.

[RainRider]

unfortunately, with this being a swapped car there is no bleed screw/bolt. does anyone have any tips/tricks to bleeding a motor swapped e30? ive read that its a self bleeding system, but that's hard to believe.

I have about the same setup. Just unhook the small overflow hose at the top of the radiator and lift the expansion tank up. And I'll squeeze the hoses to move any air around once or twice.

[mcdougal]

early e30 electric fan wiring

You really don't need to run them in series. Take the black wire off the fan plug it's not a ground! Brown is ground


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You mean take the black wire that is connected with the brown wire so that the black wire won't be connected to anything, right? So he would have red-red and black-brown?


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[mcdougal]

cant you be a little more helpful than this? You seem to have the majority of the knowledge here on swapped e30s.

I think he means that since you connected a power (black) and ground (brown) to the black wire off your fan you blew the fuse.....but I'm not sure


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[pandaboo911]

I told you to double check. I did this three years ago and am un sure of wire colors.

Use a multimeter to find the ground and the other two are low/high. Please don't burn your car to the ground