GM Service Manual Online
For 1990-2009 cars only

No 3-2 Downshift

Checks

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DEFINITION: No third gear to second gear downshift

External Automatic Transmission Control Valve Body Assembly (39)

    • 2--3, 3-4 Shift Solenoid Valve Assembly (S2) (308)
    • 1-2, 2-3, Reverse Shift Solenoid Valve Assembly (S3) (300)
    • 3-4, 4-5 Shift Solenoid Valve Assembly (S4) (303)
    • Line Pressure Control Solenoid Valve Assembly (SLT) (316)

Verify that all solenoids respond electrically. If there is no response, perform an electrical diagnosis. If there are no electrical concerns, remove the solenoid valve assemblies as needed, and inspect the solenoid O-ring seals, and the solenoid bores for signs of damage and/or missing seals. If the solenoid valves responded electrically and there are no bore or seal concerns, replace the solenoid valve assemblies 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)
    • M2 Shift Valve (426)
    • U1 Shift Valve (386)
    • U2 Shift Valve (392)

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

1-2 Reverse Clutch Assembly (19)

Remove the automatic transmission case cover and 1-2 reverse clutch assembly (19). Inspect all 1-2 reverse clutch components for proper operation. Repair or replace as necessary.