| Diagnosis and Testing Principles of Operations The steering wheel rotational movement is transferred to the steering gear through the steering column shaft. The steering gear converts this rotational movement, through the action of the rack and pinion gear into lateral movement. This movement in turn is transferred to the wheel knuckles through the tie-rods and tie-rod ends. Hydraulic fluid under pressure is supplied to the steering gear by the power steering pump. As the steering wheel is rotated, the hydraulic fluid is allowed to pass through the steering gear valve to one side of a double-acting piston, dependent on which direction the steering wheel is rotated. The fluid moves the piston, which forms part of the steering gear, giving power assistance to the effort required to steer the front road wheels. Petrol/gasolene engine variants, due to the extra load on the engine imposed by the power steering pump, have a power steering pressure (PSP) switch. The switch, which is normally closed, sends a signal to the powertrain control module (PCM) during low speed parking manoeuvres. The PCM responds by maintaining the engine idle speed. Inspection and Verification - Verify the customers concern by operating the system.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Tire pressure
- Accessory drive belt
- Wheels and tires
- Power steering line fluid leaks
| - Power steering pressure (PSP) switch
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the cause is not visually evident, verify the symptom and refer to the Symptom Chart.
Symptom Chart | Symptom | Possible Sources | Action | | The steering is very difficult/very easy | * Loose or worn accessory drive belt. | * | | * Fluid contamination. | * | | * Fluid aeration | * | | * Worn power steering pump. | * | | * Power steering hose restriction. | * CHECK the power steering hoses for damage, kinks or restrictions. INSTALL new components as necessary. REFER to Section 211-02 Power Steering. | | * Seized suspension ball joints. | * | | Moan type noise | * Routing of power steering hoses | * CHECK the security and routing of the power steering hoses. | | * Air in the power steering system | * | | * Power steering pump | * | | Whine type noise | * Power steering pump | * | | Hiss type noise | * Steering gear valve | * | | Belt noise | * Accessory drive belt worn | * | | * Loose generator/power steering pump mounting | * | | * Accessory drive belt pulley damaged | * INSPECT the water pump, generator, air conditioning and power steering pump pulleys for damage. INSTALL new components as necessary. | | Knock type noise | * Suspension components | * | | * Steering linkage | * | | The steering does not vary with increased steering wheel rotation | * Steering column to steering gear flexible coupling. | * CHECK the flexible coupling for security and damage. INSTALL a new flexible coupling as required. REFER to Section 211-04 Steering Column. | | * Worn tie-rod ends. | * | | * Worn steering column shaft. | * | | * Loose steering gear retaining bolts. | * | | * Excessive steering gear backlash. | * | | Steering assist does not vary with vehicle speed | * Power steering pressure (PSP) switch. * Circuit | * REFER to WDS. | Component Tests Steering Linkage Inspect the steering gear boots for cuts, deterioration, twisting or distortion. Make sure the boots are secure. Install new boots or clamps as necessary. - Park the vehicle on a dry, even surface and apply the parking brake. Place the steering in the straight ahead position.
- With the engine running, gently turn the steering wheel to the right and left to check free play. Free play is measured at the steering wheel rim and should be within the limits stated in the specifications. If free play exceeds the limit stated the steering linkage or the steering column is worn, or the backlash of the steering gear is excessive.
- If the steering linkage is worn, install new components as necessary. REFER to Section 211-03 Steering Linkage. The steering column cannot be repaired, install a new steering column. REFER to Section 211-04 Steering Column. Steering gear backlash can not be adjusted, install a new steering gear. REFER to Section 211-02 Power Steering.
- With the engine OFF, hold the steering wheel firmly with both hands. Attempt to move the steering wheel up and down and also to the left and right without turning the wheel, to check the steering column bearing wear, steering column shaft joint play and steering wheel or steering column looseness. If free play is detected, check the correct torque of the steering column, coupling shaft and steering wheel retaining bolts. The steering column cannot be repaired, install a new steering column. REFER to Section 211-04 Steering Column.
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