Powertrain
generic / SAE
P2781
Downshift Switch Circuit High
Voltage on the downshift switch line is above the expected window. 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.
SystemPowertrain
Typegeneric / SAE
GroupP2
Range / number7 / 81
Possible causes
- Open switch contacts high
- Switch wire shorted to B+ medium
- Connector pins corroded - high contact resistance low
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
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 60–400 €
- Estimated time: 0.5–2 h
- Component: downshift switch
- Component: wiring harness
- MIL / check engine light
Sources
References
sae:J2012