ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle with an active suspension system experiences a sudden drop in ride height on one corner and displays a 'Suspension Fault' warning. The technician connects a diagnostic scanner and retrieves a DTC indicating an open circuit in the left front ride height sensor. What is the MOST immediate consequence of this fault for the active suspension system?
- AInability to accurately control ride height and damping on that corner
- BAutomatic recalibration of all other ride height sensors
- CIncreased damping force in all suspension units
- DSystem default to a firm, fixed ride height
Show answer & explanationAnswer & explanation
Correct answer: A. Inability to accurately control ride height and damping on that corner
An open circuit in a ride height sensor means the active suspension control module cannot receive accurate data from that corner. Consequently, it cannot properly determine the current ride height or adjust the damping and ride height actuators for that specific wheel, leading to a loss of control on that corner.
Why the other options are wrong
- B. Other sensors would not automatically recalibrate; the system would flag a fault and likely enter a limp-home mode or disable active control for the affected corner.
- C. While some systems might default to a firmer setting for safety, the immediate consequence of a faulty sensor is loss of control, not necessarily an increase across all units.
- D. A system might default to a fixed height, but the primary issue is the inability to control that specific corner due to lack of sensor data.
Active Suspension Ride Height Sensor
These sensors provide continuous feedback to the active suspension control module about the vehicle's height at each wheel, crucial for real-time adjustments.
- Measures distance between body and ground/suspension arm
- Input for ride height control and damping adjustments
- Failure leads to system faults and loss of control
Memory trick: Sensor's signal gone, the control is undone.