Standby Power Supply: Service and Repair

Removing and Installing Reserve Power Source for Airbag and Belt Tensioner (up to 09/87):

NOTE: In vehicles with airbag 1/3 (recognizable from the inscription 1/3 on the test coupling/plug connection, airbag, 10-pin, X29/9), the reserve power source is removed and the plug connection is isolated.

Special Tools (Vehicles Up To 9/87):

1st Version:

NOTE: The 2nd version differs in the
- modified location of the red 10-pin plug connection from the foot rest to the plate located under the foot rest.
- modified location of the reserve power source from the foot rest to the plate located under the foot rest.

Removing:





1. Turn ignition key to position "0", disconnect battery negative terminal and cover.
2. Remove floor mat and damping elements in passenger's footwell.
3. Unscrew bolt on foot rest.





4. Pull off red 10-pin plug connection of control unit on foot rest.





5. Disconnect plug connection on reserve power source.





6. Unscrew fastening bolts and remove reserve power source.

Installing:
7. Screw reserve power source to foot rest.
8. Connect reserve power source with the plug connection (arrow).
9. Test system with tester. See "Test Program, Tests, Test Instructions for Tester..." [1][2]Component Tests and General Diagnostics
10. Check system with RS/SRS warning lamp.

2nd Version:

Removing:





X29/9 10-pin plug connection
C1 Reserve power source
2 Sheet metal clips

1. Turn ignition key to position "0", disconnect battery negative terminal and cover.
2. Remove floor mat in passenger's footwell.
3. Unscrew bolt on foot rest and disconnect foot rest.





4. Disconnect red 10-pin plug connection.
5. Pull plug connection off reserve power source.
6. Unscrew the 2 lower sheet metal clips for fastening the plate.
7. Unscrew fastening bolt and remove reserve power source.

Installing:
8. Slide holder in cutout of plate and fasten reserve power source with sheet metal bolt from the rear.
9. Connect plug connector to reserve power source.
10. Test system with tester. See "Test Program, Tests, Test Instructions for Tester..." [1][2]Component Tests and General Diagnostics
11. Continue installation in the reverse sequence.
12. Check system with RS/SRS warning lamp.