ASE A4 Suspension and SteeringSuspension System Diagnosis and RepairMedium
A vehicle with an active suspension system that uses continuously variable dampers (CVD) exhibits inconsistent ride quality, ranging from overly harsh to excessively soft, with no specific fault codes stored in the suspension control module. The technician performs a road test and observes that the damping characteristics change erratically, sometimes feeling stiff over small bumps and then soft over larger undulations. Which of the following is the MOST likely cause?
- AA mechanical binding issue within a control arm causing restricted movement.
- BA faulty ride height sensor providing incorrect input to the control module.
- CAn intermittent electrical connection to one or more damper control valves.
- DLow fluid level in the power steering system affecting hydraulic active components.
Show answer & explanationAnswer & explanation
Correct answer: C. An intermittent electrical connection to one or more damper control valves.
Continuously variable dampers rely on precise electronic control of internal valves. An intermittent electrical connection can cause erratic and inconsistent damping by disrupting the signals to these valves, leading to unpredictable suspension responses without necessarily triggering a hard fault code.
Why the other options are wrong
- A. Mechanical binding in a control arm would typically cause consistent harshness or noise, not erratic switching between harsh and soft damping.
- B. A faulty ride height sensor would primarily cause incorrect ride height or consistent ride characteristic issues, not erratic changes in damping from harsh to soft.
- D. Power steering fluid level is unrelated to the electronic control of continuously variable dampers in active suspension systems.
CVD Intermittent Connection
Continuously Variable Dampers (CVD) use electrically controlled valves to adjust damping force. An intermittent electrical connection disrupts these control signals, leading to erratic and unpredictable changes in ride quality.
- CVDs adjust damping in real-time.
- Relies on constant, stable electrical signals.
- Intermittent connections cause unpredictable damping behavior.
- May not always set a hard fault code immediately.
Memory trick: Erratic damping is often an 'INTERMITTENT' 'WIRE' problem.