Performing function test of light signals at trailer coupling socket - AN31.19-P-8100-06T

Check that light signals at trailer hitch socket (13-pin) (X58) function correctly using a light bar (1), for example.

1. Switch on left turn signal.
2. Switch on right turn signal.
3. Switch on hazard warning system.
4. Switch on side lights.
5. Switch on backup lamps.
6. Press brake pedal and check stop lamp function.
7. Switch on rear fog lamp.

   The rear fog lamp on the vehicle must not light up.

   Fig 1: Checking Light Signals At Trailer Hitch Socket (13-Pin) (X58) Function Correctly Using Light Bar

   Courtesy of MERCEDES-BENZ OF NORTH AMERICA.
8. Simulate failure of rear fog lamp on trailer.

   The rear fog lamp on the vehicle must light up.

9. Simulate failure of the left or right direction indicator lamp.

   The flashing frequency of the indicator lamp in the instrument cluster must double.

10. Insert fuse 18 in rear SAM control unit with fuse and relay module.

    Use a 20 A fuse.

11. Check constant voltage connection (terminal 30) on trailer hitch socket (13-pin) (X58).
12. Remove fuse 18 from rear SAM control unit with fuse and relay module.