GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 43846 Actuator Pressure Gage

  1. Raise the vehicle. Support the vehicle. Refer to Lifting and Jacking the Vehicle in General Information.
  2. If the vehicle is equipped with an engine skid plate, remove the four bolts that hold the skid plate in place. Remove the front skid plate from the vehicle.

  3. Object Number: 461464  Size: SH
  4. Install theJ 43846 with the air hose connecting between the air pump assembly and the front differential actuator.
  5. Tighten the adjusting knob as far as it stops.
  6. Important: Be careful not to bend any part of the hose.

  7. Turn on the ignition switch and shift transfer lever from 2H to 4H range.
  8. Make sure to check that the motor of the actuator starts running (a running sound can be heard) within 1 second and it stops when the actuator pressure gage indicates specified pressure. Check for air leakage during the procedure. Pressure specification is:
  9. Pressure Specification
    38.0 kPa (5.40-8.25 psi)

  10. Check that the pressure indicated on the gage drops as soon as the transfer lever is shifted to the 2H position.
  11. Start the motor of the actuator pump by shifting the transfer lever to the 4H position again. Loosen the adjusting knob to lower the pressure on the gage. The actuator motor should start to run again and stop in about 4 seconds.
  12. With the adjusting knob of the actuator pressure gage loosened, shift the transfer shift lever to neutral or the 2H position and then 4L or 4H position. Pump motor should stop in about 10 seconds after the motor starts to run.

  13. Object Number: 461445  Size: SH
  14. Disconnect the air hose (2) from the actuator pump assembly and connect it the front differential air hose inlet. Loosen the adjusting knob.
  15. Connect the air compressor air hose to the actuator pressure gage.
  16. Compress air into the actuator pressure gage and turn knob to obtain specified pressure. Specified pressure :
  17. Pressure Specification
    38.0 kPa (5.40 psi)


    Object Number: 461486  Size: SH
  18. While both wheels are lifted off the ground, turn one of the front wheels by hand and check the other wheel for the following:
  19. • When applying pressure to the actuator pump the other front wheel should turn in the direction opposite to the wheel being turned by hand.
    • When the actuator pump is not working (by not applying pressure) the other front wheel should remain stationary while the wheel turned by hand is turning.
    • Install the actuator pressure gage to the actuator pump assembly (1).
    • Install a voltmeter and the battery to the pump assembly (1).
    • Tighten the adjusting knob as far as it will stop and the air check side opening by a hose as a blind plug.
    • Check that the actuator assembly motor starts to run (a running sound can be heard) when the battery is connected and when it stops when specified pressure is obtained. Specified pressure is:

    Pressure Specification
    38.0-58.0 kPa (5.40-8.25 psi).

    • Ensure that the voltmeter is within specifications when the motor is running should be about 0v and when the motor has stopped it should be about 10-14 V.