Mystery cable (sorted)

[tfi_friday]

Hi,

In my idiocracy of trouble shooting the Automatic Heater Control in my 1990 325ic when putting the centre console back in I noticed a stray cable hanging loose. It's hanging about 15cm out from under the fan control so could go anywhere.

Two wires into a 4 pin plug (2 blank). One wire is black with a red stripe, the other black with a purple stripe.



Any ideas what I may have missed... Or is it something optional?

Cheers!!!

[sweep]

Iluminating gear knob?

[Brianmoooore]

Nothing to do with lights with those colours! Wire colours aren't randomly chosen, but follow a code.
The black main colours indicate that they are something to do with ignition switched live, and the red stripe and purple stripe both indicate that they are something to do with the + side of things, rather than the negative, although that's not always followed.
There's a few black/reds around the car, but the only black/purple I can think of is for the fast wiper speed request from the switch. The normal speed request is black/purple, but I can think of no reason why a plug for those two signals should be in that area.

[tfi_friday]

I've got AC so probably something I've missed...

Any idea what part it connects to?

[Grrrmachine]

Black/violet wire connects the AC switch to the ECU, according to the Wiki diagrams:

http://www.e30zone.net/e30zonewiki/imag ... ntrols.pdf

Is this the plug that connects to the little pig-tail loom at the ECU plug?

[tfi_friday]

Brilliant! Definately looks like that C136 connection.

BK/VI -> VI/GY
BK/RD -> BK/GY

Looking at the 1990 electrical trouble shooting manual, the C136 connector view is a 4 pin plug. I guess it tells the MCU that the AC is on.

Just need to find where it's physically located.

Big thanks again for the help!

[tfi_friday]

Bingo!!!





Thanks again