Component Tests and General Diagnostics
Steering System
Component Tests
Power Steering Fluid Leak Test
NOTE: This test should only be carried out if a leak in the system has not been detected during a thorough visual inspection. Refer to Inspection and Verification. Inspection and Verification
1. Remove the power steering pump reservoir cap and check the power steering fluid level. If necessary, add the specified power steering fluid.
2. Tightly install the Power Steering Evacuation Cap onto the reservoir and connect the Vacuum Pump Kit to the Evacuation Cap.
3. Using the Vacuum Pump Kit, apply 68-85 kPa (20-25 in-Hg) of vacuum to the power steering system.
4. Observe the vacuum gauge for 30 seconds. If the vacuum gauge reading drops more than 3 kPa (0.88 in-Hg), a leak is present.
5. Remove the Vacuum Pump Kit.
6. Start the engine and insert the Dial Thermometer into the Evacuation Cap.
7. NOTICE: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump may occur.
With the engine at idle, raise the power steering fluid temperature to 74-80°C (165-176°F) by rotating the steering wheel fully to the left and right several times.
8. Stop the engine and visually inspect the system for leaks.
- If a leak is evident, repair as necessary.
- If a leak is not evident, add the specified UV fluorescent tracer dye to the power steering fluid. Use 14.78 ml (1/2 oz) of dye solution for every 1.89L (2 qt) of power steering fluid.
9. Start the engine.
10. NOTICE: Do not hold the steering wheel at the stops for an extended amount of time. Damage to the power steering pump may occur.
With the engine at idle, raise the power steering fluid temperature to 74-80°C (165-176°F) by rotating the steering wheel fully to the left and right several times.
11. Stop the engine and inspect the system for traces of UV dye using the 100W/12 Volt DC UV Lamp. Repair as necessary.
Steering Gear Valve Test
1. WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury Procedures.
If equipped with a fire suppression system, depower the system.
2. With the vehicle in NEUTRAL, position it on a hoist. Refer to Jacking and Lifting Service and Repair.
- Raise the vehicle until the front wheels are off the ground.
3. NOTE: Do not hold the steering wheel while carrying out this step.
Start the engine.
- If the steering wheel rotates in either direction (with no hand input), install a new steering gear. Refer to Power Steering Steering Gear.
4. WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to Fire Suppression System. Failure to follow these instructions may result in serious personal injury Description and Operation.
If equipped with a fire suppression system, repower the system.
Steering Gear Grunt/Shudder Test
1. Start and run the vehicle to operating temperature.
2. Set engine idle speed to 1,200 rpm.
3. NOTICE: Do not hold the steering wheel against the stops for an extended amount of time. Damage to the power steering pump may occur.
Rotate the steering wheel to the RH stop, then turn the steering wheel 90 degrees back from that position. Slowly turn the steering wheel back and forth approximately one-twelfth of a full turn.
4. Turn the steering wheel another 90 degrees. Slowly turn the steering wheel back and forth approximately one-twelfth of a full turn.
5. Repeat the test with the power steering fluid at different temperatures.
6. If a light grunt is heard or a low (50-200 Hz) shudder is present, this is a normal steering system condition.
7. If a loud grunt is heard or a strong shudder is felt, purge the power steering system. Refer to Power Steering System Purging Power Steering System Purging. If a loud grunt or strong shudder still exists, check the power steering lines/hoses for restrictions or damage and repair as necessary. Refer to Power Steering Service and Repair. If the lines/hoses are OK, install a new steering gear. Refer to Power Steering Steering Gear.
Steering Linkage Test
1. WARNING: Before servicing a vehicle equipped with a fire suppression system, depower the system by following the procedure in Fire Suppression System. Failure to follow the instructions may result in serious personal injury Procedures.
If equipped with a fire suppression system, depower the system.
2. NOTE: Excessive vertical motion of the studs relative to the sockets may indicate excessive wear.
With the vehicle on the ground and the parking brake applied, start the vehicle and carry out the following:
- Have an assistant rotate the steering wheel back and forth 360 degrees and watch for relative motion of the studs in the steering linkage ball sockets.
- Watch for loose steering gear mounting.
3. As an additional check, with the Key ON Engine OFF (KOEO) and the front wheels raised off the ground, grasp the wheel at the front and rear and watch for excessive play or binding in the joints while trying to steer the wheels.
4. Install new components if necessary. Tighten any worn, damaged or loose components. Refer to the appropriate information for the procedure.
5. WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to Fire Suppression System. Failure to follow these instructions may result in serious personal injury Description and Operation.
If equipped with a fire suppression system, repower the system.