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Home › GMC › 2001 › C3500 HD 6.5 F, Automatic › Repair and Diagnosis › Steering › Power Steering System › Diagnostic Information and Procedures › Power Steering System Test › Test Description

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. 3 

    This step tests the system for restrictions.

  2. 5 

    This step tests the following components for the following conditions:

    • The pump for internal leaks
    • The power steering pipes for kinks
  3. 6 

    This step tests the ability of the pump to regulate flow at maximum pressure.

  4. 8 

    This step tests the ability of the pump to regulate flow under normal operating conditions.

  5. 10 

    This step tests the internal components of the pump and the gear.

Power Steering System Test

Step Action Values Yes No
DEFINITION: The Power Steering System Test Procedure will perform the following functions:
  • Test the operation of the hydraulic power steering.
  • Test the operation of the power steering pump and power steering gear.
  • Identify restrictions in the system.
1
NOTE:

If the power steering system has been serviced, an accurate fluid level reading cannot be obtained unless air is bled from the steering system. The air in the fluid may cause pump cavitation noise and may cause pump damage over a period of time.

IMPORTANT:

In order to accurately diagnose the system, the malfunction must be present during the test procedure.

  1. Turn the ignition switch to the OFF position.
  2. Place a drain pan under the vehicle in order to catch any power steering fluid.
  3. Disconnect the power steering pressure pipe/hose from the power steering pump or the power steering gear as necessary.
  4. Install the J 44721  Power Steering System Analyzer between the power steering pump and the power steering gear on the pressure side. Adapters may be required.
    5. NOTE:

    When adding fluid or making a complete fluid change, always use the proper power steering fluid. Failure to use the proper fluid will cause hose and seal damage and fluid leaks.

  5. Inspect and add power steering fluid as necessary in order to ensure that the power steering fluid is at the proper level and not contaminated. Refer to Checking and Adding Power Steering Fluid (Without Hydroboost) , Checking and Adding Power Steering Fluid (With Hydroboost) .
Is the fluid at the proper level and free from contamination?		 - Go to Step 3  Go to Step 2 
2 Fill or drain and refill the fluid as necessary. Refer to Checking and Adding Power Steering Fluid (Without Hydroboost) , Checking and Adding Power Steering Fluid (With Hydroboost) .
Is the fluid at the proper level and free from contamination?		 - Go to Step 3  -
3 
  1. Fully open the valve of the J 44721 .
  2. Start the engine.
  3. Refer to STEERING WHEEL IN THE FULL TURN POSITION NOTICE in Cautions and Notices.

    Turn the steering wheel and BRIEFLY hold the steering wheel against the steering stop in order to release any trapped air from the system.

  4. Inspect and ensure that none of the power steering pipe/hose connections are leaking.
  5. Make sure the steering wheel is OFF the steering stop, observe the pressure reading.
Is the pressure reading greater than the specified value?		 1525 kPa
(221 psi)		 Go to Step 4  Go to Step 5 
4
IMPORTANT:

A restriction may be present in the power steering system. Turn OFF the engine IMMEDIATELY.

Locate and repair the restriction.Did you complete the repair?		 - Go to Step 16  -
5 
    NOTE:

    When adding fluid or making a complete fluid change, always use the proper power steering fluid. Failure to use the proper fluid will cause hose and seal damage and fluid leaks.

  1. Inspect and add power steering fluid in order to ensure that the power steering fluid is at the proper level. Refer to Checking and Adding Power Steering Fluid (Without Hydroboost) , Checking and Adding Power Steering Fluid (With Hydroboost) .
  2. Allow the engine to run until the engine reaches full operating temperature.
  3. Record the pressure reading and flow reading A.
  4. Partially close the J 44721  valve until the system pressure reaches the specified value, then record the FLOW reading B.
  5. Subtract flow reading B from flow reading A.
Is the flow DECREASE greater than 3.8L (1 gal) per minute?		 4827 kPa
(700 psi)		 Go to Step 11  Go to Step 6 
6 
NOTE:

Do not leave the valve fully closed for more than 5 seconds, or the pump could be damaged internally.

Fully close then open the J 44721  valve 3 times. Record all of the high pressure readings. Refer to Power Steering Pump Specifications  for power steering system pressure relief specifications.Are the 3 high pressure readings within specifications?		 - Go to Step 7  Go to Step 13 
7 Are the 3 high pressure readings within 245 kPa (50 psi) of each other? - Go to Step 8  Go to Step 12 
8 
  1. Increase the engine speed to approximately 1500 RPM.
  2. Record the flow reading. Refer to Power Steering Pump Specifications  for power steering system pressure specifications.
Is the actual flow reading within specifications?		 - Go to Step 9  Go to Step 11 
9 Is the difference between the actual flow reading and the maximum flow specification more than 3.8L (1 gal) per minute? - Go to Step 14  Go to Step 10 
10  Refer to STEERING WHEEL IN THE FULL TURN POSITION NOTICE in Cautions and Notices.
Turn the steering wheel from steering stop to steering stop and record the FLOW readings at each stop.
Is the flow LOWER than 3.8L (1 gal) per minute?		 - Go to Step 17  Go to Step 15 
11 Replace the power steering pump. Refer to Power Steering Pump Replacement (4.8 L, 5.3 L and 6.0 L Engines) , Power Steering Pump Replacement (8.1L) , Power Steering Pump Replacement (4.3L) , Power Steering Pump Replacement (6.6L Diesel) .
Did you complete the replacement?		 - Go to Step 16  -
12
  1. Remove the power steering pump flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle (Regular) , or Power Steering Fluid Flow Control Valve Actuator Replacement - On Vehicle .
    2. IMPORTANT:

    Do NOT attempt to clean the flow control valve.

  2. Inspect the flow control valve. If any burrs or scratches are noticed on the flow control valve, replace the flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle (Regular) , or Power Steering Fluid Flow Control Valve Actuator Replacement - On Vehicle .
  3. Inspect the flow control valve bore. If any burrs or scratches are present in the control valve bore, replace the power steering pump. Refer to Power Steering Pump Replacement (4.8 L, 5.3 L and 6.0 L Engines) , Power Steering Pump Replacement (8.1L) , Power Steering Pump Replacement (4.3L) , Power Steering Pump Replacement (6.6L Diesel) .
Did you complete the repair?		 - Go to Step 16  -
13 Replace the power steering pump flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle (Regular) , or Power Steering Fluid Flow Control Valve Actuator Replacement - On Vehicle .
Did you complete the replacement?		 - Go to Step 16  -
14
    IMPORTANT:

    Do NOT disassemble the flow control valve.

  1. Remove the power steering pump flow control valve and inspect for any wear or damage.
  2. If the flow control valve is worn damaged, replace the flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle (Regular) , or Power Steering Fluid Flow Control Valve Actuator Replacement - On Vehicle .
Did you complete the repair?		 - Go to Step 16  -
15 The power steering gear is leaking across the piston or bypassing the valve circuit. Replace the power steering gear. Refer to Steering Gear Replacement (Rack and Pinion) , Steering Gear Replacement (Non-Rack and Pinion) .
Did you complete the replacement?		 - Go to Step 16  -
16 Test the power steering system for the original condition.
Does the original condition still exist?		 - Go to Step 1  Go to Step 17 
17
  1. Disconnect and remove the J 44721  from the vehicle.
  2. Connect the vehicle power steering pipes/hoses.
  3. Bleed the power steering system and add fluid as necessary. Refer to Power Steering System Bleeding .
Did you complete the repair?		 - System OK -
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