GM Service Manual Online
For 1990-2009 cars only

No Engine Braking in Third Gear

Checks

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DEFINITION: No engine braking in third gear

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 as needed, and inspect the solenoid O-ring seals, and the solenoid bore for signs of damage and/or missing seals. If the solenoid valve responded electrically and there are no bore or seal concerns, replace the solenoid valve assembly as necessary due to possible internal mechanical concerns and retest. If a condition is still present after replacing the solenoid valve assembly, replace the complete automatic transmission control valve body assembly (39).

Internal Automatic Transmission Control Valve Body Assembly (39)

    • M1 Shift Valve (389)
    • Shift Pressure Relay Valve (424)
    • Shift Pressure Control Valve (430)

Remove the automatic transmission control valve body assembly (39) and 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 any repairable concerns, replace the complete automatic transmission control valve body assembly (39).

Clutch - Mechanical/Hydraulic

    • 2nd Coast Clutch Assembly (221-230)
    • 3rd Gear Band Assembly (16)
    • Remove the torque converter assembly (1) and the automatic transmission fluid pump, 2nd coast clutch, 2nd clutch assembly (2) in order to gain access to the 2nd coast clutch assembly (221-230). Disassemble the 2nd coast clutch assembly and inspect. Repair or replace components as necessary to correct the condition.
    • Remove the automatic transmission case cover and 1-2 reverse clutch assembly (19), and the 1-2 reverse carrier gear assembly (18) in order to inspect the 3rd gear brake band assembly (16). Inspect all related components for proper operation. Repair or replace as necessary.