GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Yukon XL - 2WD 🢒 Steering 🢒 Power Steering 🢒 Power Steering System Test

Rack and Pinion System
Object Number: 649914 Size: SH
(1)Power Steering Return Hose
(2)Power Steering Pressure Hose

Recirculating Ball System
Object Number: 649922 Size: SH
(1)Power Steering Return Hose
(2)Power Steering Pressure Hose

Test Description

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

  1. This step tests the system for restrictions.

    2.

  2. This step tests the following components for the following conditions:

    3. • The pump for internal leaks

       Note: Power steering hoses may not look kinked, but have a layer separation causing the inner hose to collapse and restrict power steering fluid flow.

    • The power steering pipes and hoses for kinks

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

    4.

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

    5.

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

Step

Action

Value(s)

Yes

No

DEFINITION: The Power Steering System Test Procedure will perform the following functions:

    • Test the operation of the hydraulic power steering system.
    • Test the operation of the power steering pump and power steering gear.
    • Identify restrictions in the system.

1

Inspect the power steering fluid for the following indications of contamination:

    • Milky fluid - water
    • Brown fluid - burnt
    • Debris in fluid - plastic or dirt

Is the fluid free of contamination?

--

Go to Step 3

Go to Step 2

2

Flush the power steering system. Refer to Power Steering System Flushing.

Did you complete the procedure?

--

Go to Step 3

--

3

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

Attempt to duplicate the condition.

Is the condition present?

--

Go to Step 4

System OK

4
  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.
  5. Fill the power steering system. Refer to Checking and Adding Power Steering Fluid.

Did you complete the installation?

--

Go to Step 5

--

5

  1. Fully open the J 44721 valve.
  2. Start the engine.

    3. Caution: Refer to Steering Wheel in the Full Turn Position Caution in the Preface section.

  3. 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 all of the power steering pipe/hose connections are not 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 6

Go to Step 7

6

Note: 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 18

--

7

  1. Allow the engine to run until the engine reaches full operating temperature.
  2. Record the pressure reading and flow reading.
  3. Partially close the J 44721 valve until the system pressure reaches the specified value, then record the FLOW reading.
  4. Subtract second flow reading from the first flow reading.

Is the flow DECREASE greater than 3.8 L (1 gal) per minute?

4827 kPa

(700 psi)

Go to Step 13

Go to Step 8

8

Caution: 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 9

Go to Step 15

9

Are the three high pressure readings within 245 kPa (50 psi) of each other?

--

Go to Step 10

Go to Step 14

10

  1. Increase the engine speed to approximately 1,500 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 11

Go to Step 13

11

Is the difference between the actual flow reading and the maximum flow specification more than 3.8 L (1 gal) per minute?

--

Go to Step 16

Go to Step 12

12

Caution: Refer to Steering Wheel in the Full Turn Position Caution in the Preface section.

Turn the steering wheel from steering stop to steering stop and record the FLOW readings at each stop.

Is the flow LOWER than 3.8 L (1 gal) per minute?

--

Go to Step 18

Go to Step 17

13

Replace the power steering pump. Refer to Power Steering Pump Replacement.

Did you complete the replacement?

--

Go to Step 18

--

14
  1. Remove the power steering pump flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle.
  2. Inspect the flow control valve.

    3. If any burrs or scratches are noticed on the flow control valve, replace the flow control valve. Do NOT attempt to clean the flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle.

  3. Inspect the flow control valve bore.

    4. If any burrs or scratches are present in the control valve bore, replace the power steering pump. Refer to Power Steering Pump Replacement.

Did you complete the repair?

--

Go to Step 18

--

15

Replace the power steering pump flow control valve. Refer to Power Steering Pump Flow Control Valve Replacement - Off Vehicle.

Did you complete the replacement?

--

Go to Step 18

--

16
  1. Remove the power steering pump flow control valve and inspect for any wear or damage. Do NOT disassemble the flow control valve.
  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.

Did you complete the repair?

--

Go to Step 18

--

17

The power steering gear is leaking across the piston or bypassing the valve circuit. Replace the power steering gear. Refer to Steering Gear Replacement.

Did you complete the replacement?

--

Go to Step 18

--

18

Test the power steering system for the original condition.

Does the original condition still exist?

--

Go to Step 5

Go to Step 19

19
  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

--