C05D1Brake Master Cylinder Piston Position Sensor Supply Circuit
- Generic OBD-II code · Chassis
- Turns on the check-engine light
- Can trigger limp mode
- How the car detects it
- Fault on the reference supply of the master cylinder piston (pedal travel) sensor. GM's integrated brake controller provides two 5 V supplies, each feeding one pedal travel channel and one motor position channel; C05D1 covers the first (PTS1/MPS1), C05BB the second. The supply fails below 4.85 V or above 5.15 V for 100 ms; for erratic dips a counter adds 50 per sample towards 800 (fastest 80 ms) and latches until key-off. All are Type A with MIL in 19OBDG03D and 25OBDG04B. Because the motor position channel shares the feed, motor sensor codes can appear at the same time. Tracking regulators such as the TI TPS7B4253-Q1 show how such off-board sensor supplies are built and protected.
- What you may notice
- Malfunction indicator lamp, brake warning and loss of assist
- Further codes for pedal travel and motor position sensors
- Likely causes
- LikelySupply line shorted to ground or to another voltage
- PossiblePedal travel or motor position sensor loading the supply
- PossibleSupply circuit on the control module board defective
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €2,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.