P2685Actuator Supply Voltage C Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- P2685 means the third actuator supply rail sags while it is switched on, almost always because the line or one of the loads it feeds has a path to ground. Unlike the open and switch faults of this rail, GM's 2023 and 2024 TCM tables check this one continuously during operation: if the voltage at high-side output 7 falls below a share of the supply, or the averaged output current runs too high, a timer counts up and the fault is confirmed after 60 ms. Battery voltage must lie between 8.75 and 18 V, the engine must not be cranking, and the test is suspended when P0882 or P0883 is present; GM rates it Type A. Ford's 2024 summary lists P2685 as the shorted-load fault of high side driver 7 in the TR9070 dual-clutch unit. The protected output switches off and the transmission falls back to a failsafe mode.
- What you may notice
- MIL on during the same trip
- Failsafe gear, no normal shifting
- Blown fuse possible on the transmission supply
- Likely causes
- LikelySupply wire chafed through and touching ground
- PossibleShorted solenoid coil on this rail drawing excess current
- RareWeak battery or charging fault pulling the whole supply down
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Hard · Usually a job for a workshop.Typical cost: €100 – €1,500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.