GM Service Manual Online
For 1990-2009 cars only

No Forward and Reverse

Condition

Action

DEFINITION: No forward and reverse

No fluid or fluid level low

Inspect fluid level and color. Perform a fluid level inspection and make sure that the fluid does not smell burnt, and shows no sign of coolant cross contamination. If unable to determine if the transmission has the correct type of fluid, drain the unit and refill with the correct fluid and retest.

Torque Converter Assembly (1)

    • Torque converter (1) not physically connected to the engine flexplate due to mounting bolts not installed or physical damage to torque converter mounting lugs due to mounting bolts being too short in length. Perform an inspection of the torque converter mounting bolts to verify that they are physically present and if so, are they correct in length and size.
    • Seizure or breaking of the torque converter sleeve or fluid pump assembly (2) internal bushing, due to misalignment of the torque converter (1) pilot pin to the engine crankshaft rear center pilot hole. Inspect the torque converter sleeve and fluid pump bushing for signs of damage. If damage is present, inspect crankshaft pilot hole and correct as necessary before installing a new torque converter assembly (1).
    • Torque converter (1) to flexplate mounting bolts length are too long, thus causing internal damage to the torque converter (1) (projection into the front cover) which in turn peels off the internal friction material from the torque converter apply plate. Replace the torque converter assembly (1) and install the correct torque converter to flexplate mounting bolts.
    • Torque converter (1) internal lock-up friction material peeled off the apply plate due to an attempted thread repair on one or more of the converter mounting lug pads. Re-tapping of the mounting lug pad threads causes projection of the front cover, which in turn peels off the lock-up clutch friction material. Replace the torque converter assembly (1) and the torque converter to flexplate mounting bolts if necessary.

Physical damage to Fluid Pump Assembly, (2) due to improper Torque Converter (1) installation.

Inspect the fluid pump drive gear (205) for damage. Replace the fluid pump assembly (2) if there is damage to the gears.

External Control Valve Body Assembly (39)

Line Pressure Control Solenoid Valve Assembly (SLT) (316)

Verify that the line pressure control solenoid valve assembly (SLT) (316) responds electrically. If there is no response, perform an electrical diagnosis. If there are no electrical concerns, remove the solenoid valve assembly, inspect the O-ring seal, and bore for signs of damage and/or missing seal. If the valve responded electrically and there are no bore or seal concerns, replace the line pressure control solenoid valve assembly due to possible internal mechanical concerns and retest. If a concern is still present after replacing the line pressure control solenoid valve (316), then replace the control valve body assembly (39).