Trailer Hitch: Testing and Inspection
WM 0X01IN Trailer hitch maintenance: checking operation
Information
Required test tool
Information
- To perform this check, a trailer with no faults in the wiring and lights, or a trailer test cable VAS 1537 A is required.
- Please note that, if a VAS 1537 A trailer test cable is used, only vehicles with a 13-pin plug can be checked.
- The test cable can be attached to the trailer socket to locate faults. The plug has 13 pins; adapters are required for 7-pin sockets. Because of the build-up of heat, ensure that a thermal circuit breaker is used in the test cable.
Test cable VAS 1537 A:
Checking function of trailer hitch (AHK) socket
1. Connect the test cable to the trailer hitch socket on the vehicle and lay the cable to the front.
Overview
Test procedure
Information
- The LED for permanent positive -9- is lit for the entire duration of the test.
Figure showing inscriptions on the tester, direction indicator, brake light + with designation at the top: 1 - 13, bottom: A - D
1. Switch on the ignition and switch through the following loads in turn:
Switch on left direction indicator -1- or right direction indicator -4- - the direction indicator and the direction indicator pilot light for the trailer in the instrument cluster light up; press the relevant key -B- for left or -C- for right: now LEDs -1- or -4- and the direction indicator in the instrument cluster should not light up.
2. Actuate the brake pedal - LEDs -6- should light up.
3. Switch on the parking light - LEDs -5, 7- should light up.
4. Switch on the parking light and rear fog light - LEDs -5, 7- should light up.
Disconnect the trailer hitch plug. The rear fog light on the vehicle must light up.
5. Switch off the lights and engage reverse gear.
The back-up light on the vehicle must light up.
General:
-10- Charge positive
-11- Ground for charge positive
-12- Trailer detection
-13- Depending on the load (heat build-up) on the test equipment (the more LEDs that light up), the test equipment switches off and this is indicated by the fact that this LED lights up. Disconnect the test equipment and let it cool for at least 20 minutes.
Checking electrically retractable trailer hitch (AHK)
Information
- The swivel action of the ball hitch is interrupted in the one-touch function of the rocker switch if resistance interferes with the movement sequence. The interruption is indicated by the rapid flashing of the red LED in the rocker switch.
- Overload protection is switched off by pressing the rocker switch for at least two seconds.
WARNING
Risk of injury and damage when retracting and extending the ball hitch.
- Make sure that no persons, animals or obstacles are in the movement range of the ball hitch.
- To interrupt the swivel action of the ball hitch in the event of danger, touch the rocker switch again.
-> Never swivel the ball hitch when a trailer is coupled or when, for example, bicycle racks are mounted or supported on the ball hitch.
-> Only use the trailer coupling when the ball hitch is extended fully.
-> Never insert tools of any kind into the ball hitch swivel mechanism. This could damage the locking mechanism; safe operation of the trailer hitch can then no longer be assured.
-> Check that the ball hitch locks into position correctly before every journey.
Overload protection
Information
- The vehicle must be stationary.
- Rear lid or rear window must be open.
- The trailer must be unhitched.
- Connectors (and any adapters) must be removed from the socket.
- There must not be any accessories on the ball hitch (e.g. ball protection cap, bicycle rack, etc.).
1. Swivelling out the trailer coupling
1.1. Requirements:
Information
- The vehicle must be stationary.
- Rear lid or rear window must be open.
1.2. To swivel out:
1.3. Touch rocker switch -A-.
1.4. >> The ball hitch moves automatically into operating position.
1.5. The red LED in the rocker switch flashes until the operating position is reached.
2. Retracting the trailer hitch
2.1. Requirements:
Information
- The vehicle must be stationary.
- Rear lid or rear window must be open.
- The trailer must be unhitched.
- Connectors (and any adapters) must be removed from the socket.
- There must not be any accessories on the ball hitch (e.g. ball protection cap, bicycle rack, etc.).
2.2. To retract:
2.3. Touch rocker switch -A-.
2.4. >> The ball hitch moves automatically into operating position.
2.5. The red LED in the rocker switch flashes until the operating position is reached.
