ASE A4 Suspension and SteeringSteering System Diagnosis and RepairHard
A technician is diagnosing a power steering system that exhibits a hard steering condition in one direction (e.g., hard to turn right, normal to turn left). The power steering pump output pressure is normal in both directions during a static test. What is the MOST likely cause?
- AA collapsed power steering return hose.
- BAn internal restriction or leak within the power steering gear/rack.
- CA worn power steering pump.
- DA faulty power steering pump flow control valve.
Show answer & explanationAnswer & explanation
Correct answer: B. An internal restriction or leak within the power steering gear/rack.
If pump pressure is normal in both directions, the pump itself is functioning correctly. A hard steering condition in only one direction strongly suggests an internal issue within the steering gear or rack, such as a sticking control valve, internal bypass, or a leaking piston seal that prevents proper pressure application to one side of the piston.
Why the other options are wrong
- A. A collapsed return hose would restrict fluid flow, causing increased pressure and potentially hard steering in both directions, often with noise, not one-sided.
- C. A worn pump would result in low pressure in both directions, which contradicts the normal pump output pressure finding.
- D. A faulty flow control valve typically causes consistent low assist in both directions or specific pressure issues, not one-sided hard steering with normal pump pressure.
One-Sided Steering Gear Fault
A condition where steering assist is lost or reduced in only one turning direction, often caused by internal faults within the steering gear/rack, such as a sticking control valve or a leaking piston seal.
- Pump pressure is typically normal when tested.
- Indicates a problem within the steering gear's directional hydraulic circuit.
- Requires steering gear repair or replacement.
Memory trick: One-sided hard steer? Gear's internal error!