TCM Power Relay Control Circuit Low
The TCM power relay reports a control circuit low condition. TCM supply control is impaired. Wiring faults of this kind typically come from chafing, water ingress at connector seals, or pin push-back — a wiggle test on the harness while the code is active often confirms the location.
Affected components
- Tcm power relay
- Wiring harness
- Tcm
Common causes
- High likelihood: Control wire shorted to ground
- Medium likelihood: Internal short in coil
- Low likelihood: Connector pins corroded - high contact resistance
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.