Ride Height Sensor: Service and Repair

Vehicle level sensor






Vehicles with gas discharge headlights or air suspension have an automatic vertical aim control system as standard equipment.

To function properly, the automatic vertical aim control system needs information about compression travel or rebound travel at the front and rear axles.

For this, the position of the lower left control arm relative to the body is transferred to the left front level control system sensor-G78via a coupling rod. This sensor passes on electrical signals to the control module for the vertical aim control system.

On the rear axle these signals are passed on from the vehicle level sensor (G 76) to the control module.
For 4 wheel air suspension, 4 sensors are required (total).

These signals are needed to determine the vehicle level.

The headlight vertical aim control reacts automatically to changes in the vehicle level.

The vehicle level can change in the situations:
- Operating with something in tow
- various loading conditions; vehicle empty, vehicle partially or completely loaded;
- Driving slowly or quickly.

CAUTION!: Check adjustment of headlights!

Note: It is always necessary to check the basic setting of the headlights whenever:

- the control arm has been removed and reinstalled or replaced

Note:
- Installation work has been performed on the vehicle level sensor;
- the vehicle level sensor has been replaced;
- The retaining clip for the coupling rod on the control arm has been loosened

Basic setting of the headlights
1. Bracket
2. Vehicle level sensor (G 78)
3. Socket head bolt, 10 Nm
4. Rivet
5. Self-locking nut, 10 Nm
- Always replace after disassembly
6. Suspension strut
7. Coupling for stabilizer
8. Coupling rod from vehicle level sensor (G 78)
- Do not remove coupling link from ball head!
- Coupling rods must not be swapped for Allroad
9. Position marks on control arm for installation position of left front level control system sensor -G78
10. Front control arm, lower
11. Clip
- pry out with a slotted head screwdriver, for example
- When removing and reinstalling the track control link it is necessary to remove the metal clip.

Note: When installing linkage to the level sensor, use a 10 mm open-end wrench with dimension -A- = 4 mm to avoid damaging the seal.





- Dimension -A- 4 mm
- Wheel bolt tightening torque: 120 Nm
- The linkage for the headlight vertical aim control is fastened to the track control link between the stops using pliers.
When installing the headlight vertical aim control, make sure that the sensor crank and the linkage are in the correct orientation to one another.

Note:
- Linkage must be vertical.
- The sensor crank (arm) must point forward and downward.
- Coupling rods must not be swapped with each other for Allroad.

Level sensor in installation position- Allroad





The 4 level control system sensors G76, G77, G78 and G289 on the Audi Allroad are identical, only the brackets and coupling rods - kinematic is side - and axle specific.
Note the different color of the coupling rods at the front axle.
If the level sensor is replaced, or a connection is loosened, basic setting must be performed.