GM Service Manual Online
For 1990-2009 cars only

It is necessary to check whether or not basic automatic transmission maintenance as been carried out. The maintenance details are outlined in the "Primary check" and "Maintenance".

  1. Power supply and voltage check:
  2. The battery voltage must be 10 - 14V when the engine is stopped.

  3. AT fluid check:
  4. Check level and AT fluid condition.

  5. Stall test:
  6. Check the engine speed at stall in each range, and check the overall performance of the automatic transmission and the engine.

  7. Oil pressure test:
  8. Measure the line pressure when idling and when the engine has stalled, and check the functions of each component.

  9. Ignition timing and idling engine speed check:
  10. Adjust these if they are not within the specified ranges.

    If a problem occurs such as a "fluctuating engine speed", troubleshoot the engine first.

  11. Select linkage check adjustment
  12. Throttle sensor check and adjustment
  13. Road test:
  14. A road test is carried out to assess the problem properly and as a post maintenance check.

  15. Electrical wiring check:
  16. Check that the connectors fit securely, that the coupler has neither become rusty nor accumulated grime, that the terminals are secure and have to become distorted and that no parts have become loose or damaged.

Factors Relating To The Problem

When troubleshooting, the service technician must endeavor to reproduce the problem. It is important therefore, to try, on the basis of the technical interview, to reproduce the set of circumstances which lead to the problem initially. A patient approach to achieving this end, reproducing factors such as vibration (by manually moving the wire harness or relay), by creating heat (applying hot air) and by using water, is necessary.

Therefore, presuming that the assembly/parts may be the cause of the problem and using a tester to check the various contributory factors will make it possible to determine the behavior of the assembly/parts at the time the problem occurred.