1-2 Shift Malfunction
The TCM detects a fault during the 1-to-2 upshift. The actual gear ratio after the shift command does not match the expected ratio for second gear.
Affected components
- Shift solenoid a
- Transmission clutch pack
- Valve body
Common causes
- High likelihood: Shift solenoid A faulty
- Medium likelihood: 1-2 clutch slipping
Possible symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Diagnostic notes
- The malfunction indicator lamp may illuminate
Sources
Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.