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Home >> Hummer >> 2008 >> H2 4D Utility Wagon >> Repair and Diagnosis >> External Pages >> Different car >> Section 505 (Automatic Transmission - 2ML70 - Diagnostic Information And Procedures) >> Diagnostic Information and Procedures >> Line Pressure Check >> Auxiliary Fluid Pump

Auxiliary Fluid Pump

WARNING: This page is about a different car, the 2012 GMC Yukon, 2012 Chevrolet Tahoe, and 2012 Cadillac Escalade. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Main Fluid Pump
GM1869805Courtesy of GENERAL MOTORS COMPANY
    WARNING:

    Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.

  1. Install a scan tool.
  2. Start the engine.
  3. Inspect the transmission for the proper fluid level. Refer to Transmission Fluid Level and Condition Check .
  4. Use the scan tool to inspect for any active or stored diagnostic trouble codes. If there are any DTC's refer to that DTC table.
  5. Inspect the manual linkage at the transmission for proper function.
  6. Turn the engine OFF, connect Midtronic 165-PSC charger.
    7. WARNING:

    When the transmission is at operating temperatures, take necessary precautions when removing the auxiliary pump pressure test hole plug, to avoid being burned by the catalytic converter.

    NOTE:

    You may need to remove or disconnect components in order to gain access to the transmission auxiliary pump pressure test hole plug.

  7. Remove the auxiliary pump pressure test hole plug.
  8. Install J 45056  oil pressure gauge adapter fitting prior to conncting the oil pressure gauge.
  9. Install the J 21867  pressure gauge.
  10. Access the Scan Tool Hybrid Output Controls for the Aux Trans Pump Speed.
  11. Turn key to the Run Position but do not start the engine.
    12. NOTE:

    In order to achieve accurate aux pump pressure readings, the following procedure must be performed at least 3 times in order to gather uniform pressure readings.

  12. Use the scan tool to increase and decrease the Aux Pump Speed in increments of approximately 25%. The scan tool commands the increment values automatically starting with 25% going up to 75% and returning down to 25%. The pump should be allowed to run for 60 seconds at each commanded speed.
  13. Allow the pressure to stabilize between increments.
  14. Your pressure readings on the J 21867  pressure gauge should slightly increase with each speed command. The J 21867  pressure gauge at 25% should be approximately 60-70 PSI and end up at 75% being approximately 65-75 PSI.
  15. If the pressure readings vary greatly, refer to Auxiliary Fluid Pump Pressure High or Low .
  16. Turn the key OFF.
  17. Disconnect the J 21867  pressure gauge and remove the J 45056  oil pressure gauge adapter fitting.
    18. CAUTION:

    Refer to Fastener Caution .

  18. Install the auxiliary pump pressure test hole plug. Tighten the pressure plug to 11 N.m (97 lb in).
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