B720417 Acoustic and visual warnings indicate that the front passenger seat is occupied, and the safety belt is not fastened when the seat is actually unoccupied. If the situation is currently present, sit in the seat and move the seat to a slightl

B720417

Acoustic and visual warnings indicate that the front passenger seat is occupied, and the safety belt is not fastened when the seat is actually unoccupied. If the situation is currently present, sit in the seat and move the seat to a slightl

What’s New (Specific text highlighted):

Models removed and put into new SI B72 01 22 (This bulletin will be released in the near

future)

Correction, Procedure, Parts, Claim sections have changed

MODEL

F90 (M5 Sedan) produced to July 31, 2018

SITUATION

Acoustic and visual warnings indicate that the front passenger seat is occupied, and the safety belt is not

fastened when the seat is actually unoccupied.

If the situation is currently present, sit in the seat and move the seat to a slightly different position. The POL

(Passenger Occupancy Light) light should now function correctly.

In some cases, the air bag Warning Light was illuminated. Advanced Crash Safety Module (ACSM) fault

“930A1C - Front passenger seat occupancy detection transmitting fault (moisture)” is stored.

CAUSE

Any or all of the following can contribute to this situation:

1. Electronics (e.g., smart phones or laptops) are connected to the USB charging port or cigarette

lighter and placed on the seat.

2. The seat was wet (e.g. very high humidity, wet clothing, spilled liquids, rain).

3. Insufficient shielding of the seat heater wiring.

4. Ground for the CIS seat mat is not secure.

CORRECTION

Consultation with the customer whether objects were possibly laid on the front passenger seat or the seat

was subjected to moisture (for example: from rain through an open window, wet clothes or towel or the

spilling of fluids on the seat cushion surface).

Perform a non-invasive check for moisture / stains on the seat and at the CIS evaluation electronics module

electrical connector.

Check the CIS seat mat ground.

If there are no obvious moisture/stains, check the part number and revision index of the currently installed

seat heater (seat occupancy) combined mat assembly versus the chart in the Procedure Step 3.

If the index is lower than specified below or is one of the part numbers listed below, then the

CIS seat mat must be replaced.

If the index already greater or equal than specified below, continue diagnosis with ISTA.

Note: Do not replace the CIS electronics or the ACSM module for this situation.

PROCEDURE

For conditions that are like the situation described above:

1. Verify with the customer that no objects were lying on the seat that could have caused the

warnings.

Note: Electronic devices that are placed on the front passenger seat, e.g., laptop computers, mobile

phones, etc., could cause the front passenger airbag warning lamp to activate.

This behavior occurs primarily with devices that are connected to the vehicle electrical system via a USB

cable or other charger adapter.

In vehicles with an acoustic safety belt warning, this could cause the warning signal to sound.

2. Moisture on the seat surface can also cause a faulty seat occupancy detection. In this case ACSM fault

930A1C will be stored.

Perform a non-invasive check for signs of moisture.

a. If moisture is found, dry the mat and clear the fault. Moisture caused by outside influence is a

non-warranty issue.

b. If no moisture is found, proceed to the next step

3. The passenger restraint warning message can be triggered due to partial or no contact between the

CIS ground wire and the seat structure/frame.