GM Service Manual Online
For 1990-2009 cars only

Engagement Time From Park or Neutral to Reverse is Not Within Specifications

Condition

Action

DEFINITION: Engagement time from PARK or NEUTRAL to REVERSE is NOT within specifications

Automatic transmission fluid (ATF) level low, contaminated, or unit is contaminated with engine coolant

    • Inspect the ATF level and color.
    • Perform Transmission Fluid Check and make sure that the fluid does not smell burnt, and shows no sign of engine coolant cross contamination.
         If cross contamination is present, perform a system flush. Refer to Transmission Fluid Cooler Flushing and Flow Test .
    •  Retest to verify the repair.

Transmission is filled with the wrong type of automatic transmission fluid (ATF)

If unable to determine if the transmission has the correct type of fluid, drain the unit and refill with the correct ATF and retest.

Automatic Transmission Input Speed Sensor (73)

Inspect the automatic transmission input speed sensor (73) for loose electrical connection and/or signs of physical damage that could cause erratic output. The magnetic end of the sensor should be free of any metal shavings/particles, including heavy friction material build-up. If metal or heavy friction material is found, diagnose the cause and repair as needed. Perform a complete ATF flush on the transmission and oil cooler assembly. Refer to Transmission Fluid Cooler Flushing and Flow Test .

External Automatic Transmission Control Valve Body Assembly (39)

Reverse Shift Solenoid Valve Assembly (S5) (305)

Verify that the solenoid responds electrically. If there is no response, perform an electrical diagnosis. If there are no electrical concerns, remove the solenoid valve assembly and inspect the solenoid O-ring seals and the solenoid bore for signs of damage and/or missing seals. If the valve responded electrically and there are no bore or seal concerns, replace the assembly as required due to a possible internal mechanical concern and retest. If after reverse shift solenoid valve assembly replacement a concern is still present, replace the complete automatic transmission control valve body assembly (39).

Internal Automatic Transmission Control Valve Body Assembly (39)

    • Shift Pressure Relay Valve (424)
    • Shift Pressure Control Valve (430)
    • Remove the automatic transmission control valve body assembly (39) to inspect the items listed.
    •  Inspect the internal bores and the valves for signs of wear and/or damage, including internal contamination.
         If unable to verify a repairable condition, replace the complete automatic transmission control valve body assembly (39).

Clutch - Mechanical/Hydraulic

    • Direct Clutch Assembly (562)
    • Low and Reverse Clutch Plates and Disc Assembly (26)
    • Remove the automatic transmission case cover and 1-2 reverse clutch assembly (19), the forward and direct clutch assembly (23), the front internal gear and low clutch sprag assembly (25), and the low and reverse clutch plates and disc assembly (26).
    •  Inspect all related components for proper operation.
    •  Repair or replace as needed.