Chevrolet Silverado / GMC Sierra. Service manual — part 2705

3

Attempt to duplicate the condition.Is the
condition present?

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

-

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. See Special Tools.

5. Fill the power steering system. Refer

to Checking and Adding Power
Steering Fluid (With Hydroboost)
or Checking and Adding Power
Steering Fluid (Without
Hydroboost).

Did you complete the installation?

-

Go to Step 5

-

5

1. Fully open the J 44721 valve. See

Special Tools.

2. Start the engine.

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.

NOTE:

Refer to STEERING WHEEL IN THE
FULL TURN POSITION NOTICE .

1525 kPa

(221 psi)

2008 Chevrolet Silverado 1500

2008 STEERING Power Steering - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

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?

Go to Step 6 Go to Step 7

6

Locate and repair the restriction.Did you
complete the repair?

IMPORTANT:

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

-

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. See Special Tools.

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

Fully close then open the J 44721 valve 3
times. See Special Tools. Record all of the
high pressure readings. Refer to Power
Steering Pump Specifications for power

NOTE:

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

-

2008 Chevrolet Silverado 1500

2008 STEERING Power Steering - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

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 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?

NOTE:

Refer to STEERING WHEEL IN THE FULL
TURN POSITION NOTICE .

-

Go to Step

18

Go to Step

17

13

Replace the power steering pump. Refer to
Power Steering Pump Replacement
(4.3L) or Power Steering Pump
Replacement (4.8L, 5.3L, 6.0L, and
6.2L) or Power Steering Pump
Replacement (6.6L).
Did you complete the replacement?

-

Go to Step

18

-

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.

2008 Chevrolet Silverado 1500

2008 STEERING Power Steering - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

14

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.

If any burrs or scratches are present
in the control valve bore, replace the
power steering pump. Refer to
Power Steering Pump
Replacement (4.3L) or Power
Steering Pump Replacement
(4.8L, 5.3L, 6.0L, and 6.2L) or
Power Steering Pump
Replacement (6.6L).

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

-

The power steering gear is leaking across
the piston or bypassing the valve circuit.

2008 Chevrolet Silverado 1500

2008 STEERING Power Steering - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado