Unofficialbmw.com

[alexgraf]

Hi:
The seat belt light of my E39 stays on when the seat belt is latched. It started intermittently (latching and unlatching the drivers side belt did the trick) but now it always on. The short side (attached to the seat) has an electrical cable that I supposed sends a signal when the seat belt is on or off. Is it there any way to test if this sensor is working, before I go through the trouble of removing the seat. The seat is a comfort electric.

Thanks ...

Alex
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'95 325is


'99 528iT - a real SUV

[edjack]

I wouldn't exactly say it would be easy, but the dealer can diagnose the switch using their DIS/MoDIC system, via the SRS bus.

Otherwise, if you DIY, you'll need to pull the buckle and examine the connections inside. The SI excerpt mentioned "Defective printed circuit board or contacts of the seat buckle switch, are causing resistance values to fluctuate under mechanical load."

You might try a blast of compressed air into the buckle slot in case there's some debris in there.
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Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[alexgraf]

Thanks Ed Jack. I took the car to my good mechanic to read the codes, and to change the PCV valve. I realized that was going to take most of a good weekend to do that job. I will update the forum after I get the car back.
_________________

'95 325is


'99 528iT - a real SUV

[alexgraf]

The mechanic changed the seat belt buckle and now the seat belt light never lights up, even with the seat belt not engaged. Is it there any "setting" to allow the light to come on? I have had no time to return the car to the shop yet.
_________________

'95 325is


'99 528iT - a real SUV

[edjack]

Sounds like an imcomplete repair. Back to the mechanic.

The car is supposed to nag you until you buckle up.
_________________


Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.

[alexgraf]

I figured. Will try next week. Thanks !!!
_________________

'95 325is


'99 528iT - a real SUV

[edjack]

Pin 4 of the seat belt connector is supplied with 12V. Pin 3 sends a signal to the SRS control module, which I would expect to be 12V.

Bentley shows a transistor in the buckle, but I suspect it's a microswitch.

Just for fun, try a blast of compressed air into the slot where the tang goes.
_________________


Ed BMW CCA member since 1987 (Nr. 62319).
'97 540i 6 speed Aspensilber over Aubergine interior.