P2757

Symptoms

• Check engine/service light
• delayed or harsh gear changes
• shudder or vibration during acceleration
• delayed torque converter clutch engagement — the vehicle feels like it is slipping under load
• especially climbing hills or merging onto a highway
• engine revs higher than normal for a given road speed
• reduced fuel economy.

Probable causes

• 1) Defective torque converter clutch solenoid. 2) Wiring/connector issues — corrosion in the external harness or a loose pin in the internal transmission harness. 3) Valve body problem — the bore where the TCC solenoid sits may be worn
• causing pressure leaks. 4) Bad torque converter. 5) Degraded or low transmission fluid. 6) Malfunctioning TCM. 7) Internal transmission failure.

Diagnostic steps

1. Scan for codes and review freeze frame; note any companion transmission codes.
2. Check transmission fluid level and condition first; correct low or degraded fluid before further diagnosis.
3. Inspect the external wiring harness and connectors for cracks, chafing, and corrosion; with a multimeter verify 12V supply and ground continuity at the connector.
4. With a scan tool, monitor the TCC solenoid duty cycle, torque converter clutch pressure (if available), and transmission temperature during a road test under acceleration — a duty cycle stuck at 0% confirms a stuck-off command.
5. Test the TCC solenoid itself and inspect its valve body bore for wear/pressure leaks; repair or replace as needed.
6. If solenoid, circuit, and valve body test good, evaluate the torque converter and internal transmission condition.
7. Some fixes require TCM re-programming or replacement — verify with the factory service information.
8. Do not defer the repair: driving without TCC lockup overheats and degrades the fluid and can lead to internal clutch failure.