Seat occupancy sensor

[DanielS]

This is probably a very silly question, yet at the moment I am rather confused.

I was able to buy some electric memory seats with heaters for a bargain price, did have to drive for a hour to pick them up, but very well worth it. They are in much better condition then my old manual seats with heating.

So tonight I took out the old seats, disconnected the yellow harness and put the new seats in. As I assumed ( :headbang: ) it would be just plug and pray. Yet both my new seats had a white electrical harness that I could not place. So I figured as they came out of a Z4M they might have some wires that I would not use. Turned the ignition on and the seats are working just fine, except the seat heating. The car isn't giving me any errors on the dashboard.

Now after taking the old seats back inside, I discovered that only my old passenger seat had a seat occupancy sensor part number 65776927500. The drivers side did not have the sensor installed.

So tomorrow I will install the passenger side occupancy sensor back in again, but should I not order another sensor for the drivers side? If I look at realoem they only mention 1 sensor? and will this fix the heating issue or should I look elsewhere?

 

[DMike]

Hi Daniel,
The driver’s seat does not have an occupancy sensor, the logic being that if in a crash, it is most likely that there is a driver seated behind the wheel.
The seat heating issue is unrelated as far as I understand.

 

[DanielS]

Thanks, will get the passenger side out tomorrow and install the sensor. Will double check that harness for wiring for the heating.

 

[DMike]

The M seats should have the sensor mat from factory. I you did not get the airbag light, then it’s even compatible (there has been two versions of detection) or there is an ebay bypass module installed. Anyway, without airbag light you should be good to go. The module 65776927500 you had in your old seats was used in the earlier version of the occupancy detection.

Regarding the heating, if your battery is low on voltage, the logic board won’t switch the heating on. Did you try it with the engine running or just the ignition on? The board can also throw error codes. There’s more on WDS about testing the heating.

 

[Zulu4]

Maybe the 'white harness' is for aftermarket seat heating elements (like mine).

 

[DanielS]

Today the weather was just bad... all day drizzle... so in between when there was like 10 minutes to spare I would pop out, uncover the car, get working and then pop back inside when there was proper rain.

Detached the passanger side and attached the occupancy sensor. So got that sorted and when I was doing this I mad the discovery that my yellow conncetor on the seat was not rather loose. Got the seat out of the car on it's side and found the passenger side issue. The chair connector was just broken on one side. Meaning that the chair wire would be pushed out when I would connect the car side of things. Took me a while to get this sorted. But got every wire and connector in there smoothly. Poof... passenger side all good, seat heating, all working.

So even before detaching the drivers side of the car, I gave the the wires and connectors a check and indeed the same issue on the drivers side. Having tacked this on the passengers side of the car it took me less than 5 minutes to get that sorted and all is good! I have fully functioning heated memory seats!

I do feel a bit dumb not having found this earlier...

A big thanks for @DMike for sending me all the information on fixing the issue!! Many thanks!!

 

[DMike]

Glad you got everything sorted!