P2781Downshift Switch Circuit High
- Generic OBD-II code · Powertrain
- How the car detects it
- P2781 sets when the downshift switch input climbs above its upper voltage limit. GM's 2023 dual-clutch TCM tables cap the TAPDN signal at 4.774 V; staying above it for 150 ms produces a Type C entry, no MIL. Ford's TR9070 table in the 2024 summary uses P2781 for the out-of-window-high case of the downshift paddle. GM has a field case: Service Update N212350930 (February 2024) covers about 23,500 Chevrolet Corvettes of model year 2021 whose TCM wrongly reported P2781 as permanent, which could fail an inspection that reads permanent codes; the fix is new TCM software. Real faults are mostly an open signal or ground wire or a loose plug at the wheel. P2780 is the low-side twin, P2779 the in-range plausibility fault.
- What you may notice
- Downshift paddle not working
- Permanent code shown at an emissions inspection although the paddle works (software case)
- Likely causes
- LikelyOpen signal or ground circuit, loose connector at the wheel
- PossibleTCM software reporting a false permanent code (2021 Corvette, N212350930)
- PossibleBroken track in the clock spring
- Repair
- Medium · Usually a job for a workshop.Typical cost: €0 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.