Heated Seats Wiring Diagram

[M3KUK]

Anyone have a wiring diagram for heated seats?
Got one in my Haynes Manual but it's not perfect.

[Brianmoooore]

http://www.autolib.diakom.ru/CAR/BMW/19 ... /fig05.pdf

[M3KUK]

Brilliant! Thanks Brian.

[M3KUK]

Err, wired them up on the bench as per that diagram and no worky! That diagram shows 1 and 2 for seat base element and 3,4 for backrest. Don't see how that can work as low heat setting puts 12V to pin 1 and pin 4 for earth.

[Satan]

Are you using original pads or after market ones as I think original pads go to a 4 wire connecter and aftermarkets are 3 wire?

[M3KUK]

Original wth 4 pins.

[Satan]

Should be no issues then, lead/loom from accessories socket receptacles for both switches then loom to each seat to a 4 pin connector (can't remember male or female) which plugs in to the opposing connector where the cables from both pads per seat terminate.

Do you just need to know the pin layout for the connectors?

[Satan]

https://www.r3vlimited.com/board/showth ... p?t=224101

[Brianmoooore]

as low heat setting puts 12V to pin 1 and pin 4 for earth.

That's correct. 12 volts to pin 1, the red/yellow from pin 2 is shown connected to the yellow from pin 3, connecting the two elements in series, and pin 4 is earthed, completing the circuit.
You can see from the circuit diagram that on full heat, pin 1 is earthed, and 12 volts is applied to pins 2 and 3, giving the full 12 volts across each element.

[M3KUK]

Thanks, I think I had the elements connected the wrong way round, I have checked with the BMW instructions and think it is now correct.

Pin 1 Red
Pin 2 Yel/Red (seat base element)

Pin 3 Red
Pin 4 Yel/Red (seat back element)

[M3KUK]

I'm using 2 of the seat base ones as back rest one NLA btw.

[Brianmoooore]

It doesn't matter which way around each element is connected. Pin 1 and 2 can be swapped, 3 and 4 can be swapped, and 1 and 2 as a pair can be swapped with 3 and 4 as a pair.

[M3KUK]

Now sorted! Operator error(as usual), the power supply I was bench testing with wasn't rated high enough to power the seats on high setting. Thanks again!