Electric/Auxiliary Transmission Fluid Pump B Underspeed
The auxiliary transmission fluid pump B falls below the calibrated minimum speed for the commanded duty. Mechanical resistance high or supply voltage low.
Affected components
- Aux transmission pump b
- Transmission fluid
Common causes
- High likelihood: Pump mechanically binding
- Medium likelihood: Supply voltage low under load
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
- Reduced-power or limp mode may occur
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.