Suspension Control ( Automatic - Electronic ): Specifications

Component specification

Shock absorber solenoids

General





Type
Damper solenoids: Wire wound solenoids that regulate valves in the shock absorbers.

characteristic
Damper solenoids: Resistance between terminals #1 and #2 should be approx. 5 ohms at +20 °C.
Resistance decreases with increasing temperature.

Other information
In the event of a fault in the Four-C system, the dampers function as standard passive dampers.

Terminal










Check
Prerequisites (unless otherwise specified):
- Measure in solenoid's connector.
- Ignition switch position 0.

Check 1
Damper solenoid:
Measure resistance between terminals #1 and #2. The value should be R approximately 5 ohms at +20 °C.

Acceleration sensor body

General





Type
Acceleration sensor: Capacitive micromechanic sensor. Output signal 0 - 5 V is proportional to acceleration.

characteristic
Acceleration sensor: Voltage between terminals #1 and #2 should be approx. 2 V when vehicle is stationary. Voltage fluctuates around this value during accelerating movements.

Other information
The front acceleration sensor and rear acceleration sensor are not the same. If an acceleration sensor does not have supply voltage, the input signal to the suspension module (SUM) becomes approx. 2.36 V (no diagnostic trouble code for such).

Terminal










Check
Prerequisites (unless otherwise specified):
- Breakout box connected.
- Sensor connected.
- Ignition switch position II.

Check 1
Acceleration sensor:
Measure the power supply for the acceleration sensor in question. The value should be: U approximately 5 V at ignition switch position II.

Check 2
Acceleration sensor:
Measure the voltage between signal and ground for the acceleration sensor in question. The value should be U approximately 2 V with the vehicle stationary.

The signal fluctuates around 2 V when the vehicle accelerate vertically (is rocked)

Height sensor

General





Type
Height sensor: Hall sensor with magnet in rotor, ASIC, that detects the angle of the magnetic field. Output signal 0 - 5 V is proportional to angle. Measurement range: -35 degrees to +35 degrees.

characteristic
Height sensor: Voltage between terminals #1 and #2 should be approx. 2.5 V at rest and when vehicle is stationary. Voltage fluctuates around this value during vertical movements.

Other information
Height sensors on the right and left side have differing output signals during compressed/extended suspension. During compressed suspension, the sensors on the left side have a signal of about 0.5 V while those on the right have a signal of approx. 4.5 V. During extended suspension, sensors on the left side have a signal of approx. 4.5 V while those on the right have approx. 0.5 V.

Terminal










Check
Prerequisites (unless otherwise specified):
- Breakout box connected.
- Sensor connected.
- Ignition switch position II.

Check 1
Height sensor:
Measure the power supply for the height sensor in question. The value should be: U approximately 5 V at ignition switch position II.

Check 2
Height sensor:
Measure the voltage between signal and ground for the height sensor in question. The value should be U approximately 2.5 V with the vehicle stationary.

The signal fluctuates around 2.5 V when vehicle height changes (increased/reduced load)

Switch

General





Type
Switch with different load resistance can be connected. Depending on the voltage in the switch, the control module can detect which button has been actuated. Indication via LEDs, background illumination.

characteristic
Voltage on the signal conductor from the switch should be approx. 1.63 V at Comfort position, approx. 2.65 V at Sport position and approx. 3.45 V at Advanced position.

Terminal






Check

Check 1
Switch:
Measure the power supply. The value should be U approximately 5 V at ignition switch position II.

Check 2
Switch:
Measure the voltage between signal and ground for the switch. The value should be U = 1.559 - 4.322 V depending on the driving program selected with the switch.

Comfort driving program. U = 1.559 - 2.050 V
Sport driving program. U = 2.554 - 2.916 V
Advanced driving program. U = 3.349 - 3.632 V
Switch not actuated: U = 4.110 - 4.322 V