TCM Power Input Signal High
TCM main supply voltage exceeds the operating threshold, typically caused by a faulty voltage regulator on the alternator.
Affected components
- Tcm
- Alternator
- Voltage regulator
Common causes
- High likelihood: Alternator overcharging
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.