Code 21 - 2ND Gear Stuck On: Description

PCM should release 2nd gear clutch by closing ground circuit of 2nd line actuator. PCM can detect transaxle gear position by comparing the Vehicle Speed Sensor (VSS) input to the Turbine Speed Sensor (TSS) input. Code 21 is set if transaxle should be in 1st gear, but PCM currently detects a speed equal to 2nd gear operation.

1. If present, go to information flag listed. Using flow charts, check for possible causes of trouble code.
2. See ACTUATOR QUICK CHECK  under SELF-DIAGNOSTICS. Ensure clicking sound from 2nd line actuator is similar to clicking sound of other line actuators.
3. Remove valve body. Apply air pressure to 2nd apply port. See HYDRAULIC PRESSURE TESTS in AUTO TRANS OVERHAUL - SATURN article.
4. Cross-channel leaks may cause 2nd gear to be applied all the time. If code 21 is present and no reverse is possible, check for damaged end cover input hub seals.
5. This step checks for 2nd clutch operation. If clutch applies and releases, check valve body. If clutch does not operate okay, check for damaged end cover or other internal problem.