Where to get Ignition wire in engine bay

[kalib0y]

I would like my puller fan to turn on when I start the car. where can I tap into a good ignition source?

I do not use my cruise control, is there an ignition wire there I can use? If so which color wire would it be?

I tried to look up the e30 wiring diagram and am a little confused to be honest with you guys.

thanks for your help

[Danny]

Off the main relay, red and white wire. I just jammed a wire into the socket and pushed the relay down, worked fine for me. That's hella ghetto though to be honest. You could use a multi meter and see if there is one on the cruise harness, I'm going to guess it's yellow.

[herlsy]

Honestly i wouldn't want my fan to run more than it has to, especially the whole time the car is on. I ended up splicing into the thermoswitch on the radiator so it kicks on high speed when needed. Here is my diagram:

[rThor432]

^^That is much more ideal than a fan that sees constant power with the ignition switched on. At the very least you should run a simple On/Off switch.

[kalib0y]

well I will run an additional T-stat so it turns on when I want it to becuase I already have a large pusher up in front that is running on the stock fan switch. I am still running AC so the extra puller will work nicely so I just need a good source for ignition it doesnt run when the car is switched off.

[kalib0y]

Any other input?

[herlsy]

I think the 12v switched is usually a solid green wire either side of the c101, there could also be a splice location either under the dash or inside the fuse box.

[Matt-B]

i have an auto harness. im using switch power off that

[DaveSmed]

I'm assuming everyone is adding a fan in addition to their stock aux. fan? If not, why not use the stock wiring?

[george graves]

Does the 24v harness have a diagnostic connector?

[Matt-B]

yes

[kalib0y]

I ended up tapping into the main relay (red and white wire) and the system works like a charm. I will post up my whole set up in another thread. Works flawlessly and doesn't go past half.

[etxxz]

^^ i did this the first time, i didn't like having wires all over my engine bay.

i then used the 2temp switch on the radiator, for the OE Aux fan, and that worked well, but i never had peace of mind so i'm went back to the first method, in-cabin switch, but i tucked my wire whole wire harness through the fender. looks sick.

[DaveSmed]

The OE stuff runs in the factory loom, through relays, through fuses conveniently located in the fusebox.... You really can't do it any cleaner. And it's good enough reliability for BMW, so it should do just fine.

[George77]

If you have the A/C wiring harness still you can use the stock plug(connect it to T1 and C) for the auxiliary fan and whenever you want the fan on you just pres the A/C button and the fan will kick in.