2018-2021 BMW X3/X4 Knee Air Bag Wiring Harness Repair

BMW has released Service Information Bulletin (SIB) 65 01 22 to address an issue affecting the knee airbag system in certain 2018-2021 BMW X3 (G01, F97) and X4 (G02, F98) models. This bulletin, which is Revision 6 and replaces the August 2023 version of SI B65 01 22, details a repair for problems with the knee airbag wiring harness.

This SIB 65 01 22 is crucial for owners experiencing specific warning lights and fault codes related to their vehicle's restraint system. The repair involves replacing and protecting the knee airbag wiring to prevent future chafing and ensure the system functions correctly.

Symptoms

Owners of affected BMW X3 and X4 vehicles may notice a specific set of symptoms indicating a problem with the knee airbag system. The primary indicators are:

• A "check control message (CCM) for the restraint system (Air bag) appears."
• In the instrument cluster, "the red air bag warning light lights up permanently."

These warnings suggest an issue that requires immediate attention to maintain the safety and integrity of the vehicle's airbag system.

Fault Codes / DTCs

When these symptoms occur, the Air Bag Control Module (ACSM) will typically store specific diagnostic trouble codes (DTCs). These codes help technicians pinpoint the exact nature of the knee airbag fault. The following fault codes may be stored in the ACSM (air bag control unit):

Code	Description
930949	Knee airbag, driver: short circuit to negative terminal
93094F	Knee airbag, front passenger: short circuit to negative terminal
93094C	Knee airbag driver's side: Resistance too great
930952	Knee airbag, front passenger: Resistance too great

If your vehicle exhibits a BMW X3 knee airbag fault and these codes are present, it strongly indicates the wiring harness issue described in SIB 65 01 22.

Cause

The root cause of this problem is mechanical wear on the knee airbag wiring harness. Over time, the wiring harness leading to the knee airbag(s) can rub against the metal support tubes that form part of the instrument panel structure. This constant friction leads to chafing and damage to the wiring, which then triggers the warning lights and fault codes.

Correction Overview

The repair outlined in SIB 65 01 22 focuses on replacing the damaged wiring and preventing future chafing. The general steps involve gaining access to the affected components, replacing the wiring harnesses, and adding protective measures. Importantly, the dashboard cover and the knee airbags themselves do not need to be removed for this repair.

Repair Procedure Summary

BMW Service Information Bulletin 65 01 22 details a comprehensive procedure for addressing the knee airbag wiring harness issue. Technicians will follow these steps:

1. Initial Vehicle Test: A vehicle test is performed using the ISTA diagnostic system.
2. Center Console Removal: The center console is removed according to Repair Instructions 51 16 165 to access the Air Bag Control Module (ACSM) wiring connector (A11*2B). The ACSM module is then inspected for any signs of corrosion within its electrical connectors.
3. Driver's Side Trim Removal: The under-dash trim panel on the driver's side is removed, following Repair Instructions 51 45 184. The connector (B8*1B) for the driver's side knee airbag is unplugged, and the existing knee airbag wiring harness is cut near the connector and tied back with a cable strap.
4. Passenger's Side Trim Removal: Similarly, the under-dash trim panel on the passenger's side is removed using Repair Instructions 51 45 195. The connector (B77*1B) for the passenger's side knee airbag is unplugged, and its wiring harness is cut near the connector and tied back.
5. Wiring Protection: Felt tape (part number 54 34 7 248 700) is applied generously to the dash support bracket and corresponding edges where the knee airbag wiring could chafe. It is critical that the felt is glued around the entire edge for effective protection.
6. ACSM Connector Disconnection: The wiring connector from the ACSM (A11*2B) is unplugged.
7. Wire Identification and Cutting: Technicians must reference the 'Airbag firing circuits' Wiring Diagram (SP0000061332) to confirm the wire color and pin numbers before cutting the four specific wires at the ACSM connector. These wires are then cut and tied back with a cable strap. The wires are:
   • ACSM Pin 25 (A112B) to driver knee airbag (B81B) Pin 1.
   • ACSM Pin 20 (A112B) to driver knee airbag (B81B) Pin 2.
   • ACSM Pin 5 (A112B) to passenger knee airbag (B771B) Pin 1.
   • ACSM Pin 10 (A112B) to passenger knee airbag (B771B) Pin 2.
8. Repair Cable Installation: Two new repair cables are pinned into the airbag control unit connector (A11*2B).
9. Harness Wrapping and Routing: The knee airbag wiring harnesses are wrapped with an abrasion-resistant fabric tape (part number 61 13 6 925 452). One repair harness is routed to the driver's side knee airbag, and the other to the passenger's side knee airbag.

Required Parts

To perform the repair described in SIB 65 01 22, specific parts are required. The bulletin notes that the exact part numbers should be determined by entering the VIN/chassis number into ETK or AIR to account for specific vehicle equipment. However, the following general parts are listed:

Part Number	Description	Quantity
61 12 5 A56 386	Repair wiring for airbag system (Knee air bag)	2
54 34 7 248 700	Felt strip, self-adhesive (130 x 40 x 3 mm)	Up to 4/cut to size
61 13 6 925 452	Fabric adhesive tape abrasion resistant (25 mm x 25 m, DN price = 1 meter)	Up to $5.00

Important Warnings for Owners and Technicians

This Service Information Bulletin includes several critical points to ensure the correct and efficient execution of the repair, and to inform owners:

• "The dashboard cover does not need to be removed."
• "The knee air bags do not need to be removed."
• "Both replacement harnesses are to be installed, even if there is only a fault showing for one side."
• "The replacement harnesses do not need to follow the same exact routing path as the original."
• "Important: The felt must be glued around the edge!"
• Technicians must "confirm the wire color and pin number BEFORE cutting these 4 wires at the ACSM connector."

This repair is covered under the terms of the BMW New Vehicle Limited Warranty for Passenger Cars and Light Trucks, using Defect Code 6112900300, which describes a "G0x F9x Check Control message, restraint system (wiring harness, knee airbag)" issue. If you are experiencing a BMW X3 knee airbag fault, contact your authorized BMW dealer for diagnosis and repair.

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Source: NHTSA ID 10246225