Coolant Pump A Control Circuit Stuck On
The first coolant pump runs even when no command is active. Driver is stuck on or the wire is shorted to a permanent supply.
Affected components
- Coolant pump a
- Control module
- Wiring harness
Common causes
- High likelihood: ECU output driver stuck on
- Medium likelihood: Control wire shorted to a permanent B+ supply
- Low likelihood: Carbon or debris buildup preventing free movement
Diagnostic notes
- The malfunction indicator lamp may illuminate
Related codes
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.