Dynamic Traction Control (DTC)
To improve propulsion, the ASC slip thresholds can be increased up to a speed of 45 mph (70 km/h). The permissible slip is doubled which offers advantages when driving on poor roads and in heavy snow (increased rear wheel spin is permissible).
When chassis dynamics increase as measured by the yaw rate sensor, the slip thresholds are reduced back to the normal mode for stability reasons. The DTC function can be activated/deactivated by the Controller in the Control Display menu.
When the DTC traction mode is activated, the "DTC" light is illuminated above the DSC safety light (in the instrument cluster).
Scheme 3
Diagnosis
System monitoring and plausibility: For safety reasons, faults with one damper valve will result in deactivation of all damper valves. Fault detection takes place on each axle. To pinpoint which valve is faulty, use the DISplus to measure the resistance of the individual valves (per axle). The resistance of a good valve is 2.2 ohms +/-10% at room temperature (20 °C).
Acceleration sensors: The EDC-K control module does not distinguish individual malfunctions between the sensors. The power supply to the three sensors is connected in parallel in the control module (without isolation). A short circuit in the supply voltage to one of the sensors will also affect the supply to the other sensors.
A maximum of seven different faults can be stored for the acceleration sensors. The coding data will indicate the functions of the control module (vehicle and country specific).
The following component faults can be detected
| Component | Type of fault | Fault detection via |
|---|---|---|
| ARS control module | De-energized or faulty | Instrument cluster via omission of the Alive-Counter, vehicle identification number with authentication not recognized, watchdog |
| Pump | No pressure | Target-performance comparison pressures |
| Directional valve | Stuck in the "energized" position (wire break) | Directional valve sensor |
| Stuck in the "de-energized" position (wire break) | ||
| Pressure control valve | Open (de-energized) | Front axle target-performance comparison pressure, current Measurement |
| Closed (mechanical fault) | Front axle target-performance comparison pressure | |
| Pressure control valve | Open (de-energized) | Rear axle target-performance comparison pressure and current measurement. |
| Closed (mechanical fault) | Rear axle target-performance comparison pressure | |
| Fail-safe valve | Stuck open | Predrive-Check |
| Stuck closed | Current measurement | |
| Actuator Front/rear axle | Leaking (no moment) | Target-performance compliance pressure |
| Blocked | Target-performance comparison pressure | |
| CAN bus | Completely omitted (line out) | CAN-timeout |
| Steering angle | Implausible, or omitted | Plausible monitoring and fault detection CAN bus signals |
| Sensor | Completely omitted (line out) | Voltage monitoring |
| Incorrect signal | Check plausibility via CAN signals | |
| Fluid level sensor | No signal (line) | |
| Front axle Pressure sensor | No signal (line) | Front axle target-performance comparison pressure |
| Incorrect signal | ||
| Rear axle pressure sensor | No signal (line) | Voltage monitoring |
| Incorrect signal | Target-performance comparison pressure | |
| Directional valve sensor | No signal | Voltage monitoring |
| Incorrect signal | SSE directional valve target - performance comparison |
DIAGNOSIS
Depending on the fault, the system exhibits one of the reactions listed below
Scheme 4
A 12 Pin Adapter Cable, Special Tool # 90 88 6 372 040 is used in conjunction with the DISplus to adapt the MFK cables when diagnosing the ARS system.
