Fault Code A Or B
- This code sets when SRS control unit detects a short to ground, short to battery or an open circuit at terminal 2 (Blue/Gray wire) of 2-wire Orange connector X784 (Brown/Gray and Blue/Gray wires) at SRS control unit.
- Disconnect X784 connector at SRS control unit. Connect SRS Test Connector (88-6-621-260) to SRS control unit. Using BMW Service Tester, measure resistance between terminals No. 2 (Blue/Gray wire) and No. 1 (Brown/Gray wire - male end). If resistance is NOT 3-5 ohms, go to step 3). If resistance is 3-5 ohms, perform the following;
- For fault Code "A", check these two wires for short to ground or short to battery voltage and repair/replace as required. If no problem exists with wiring, replace SRS control unit.
- For Code "B", replace diagnostic SRS control unit.
- Disconnect 2-wire Orange connector X783 (Brown/Gray and Blue/Gray wires, and Brown and Blue wires) of SRS wiring harness to contact ring, located on steering column. Connect SRS Test Connector (88-6-621-260) to contact ring side of harness connector X783.
- Measure resistance between terminal No. 2 (Blue wire) and terminal No. 1 (male end of Brown wire). If resistance is NOT 3-5 ohms, go to step 5). If resistance is 3-5 ohms, check for open circuit in Brown/Gray and/or Blue/Gray wires from X784 connector at SRS control unit to X783 connector and repair connections if possible otherwise replace wiring as required.
- Remove air bag module from steering wheel and disconnect its plug connector. Connect SRS Test Connector (88-6-621-260) to contact ring side of X783 Orange connector on steering column, and connect together the ends of SRS test connector.
- Using BMW service tester, connect leads to air bag module/contact ring connector in steering wheel and measure resistance. If resistance measures between 1.4 and 1.8 ohms, replace air bag module. If resistance is not between 1.4 and 1.8 ohms, replace contact ring.