A lot of performance oriented vehicles allow you to manually downshift the transmission by either pushing/pulling the gear selector or tapping the ‘-‘ paddle shifter behind the steering wheel. If there is an unusually high voltage coming from the downshift switch that enables this function, a P2781 DTC will be saved.
How Serious is the Code?
As far as severity, a P2781 diagnostic trouble code is not really going to affect the way your vehicle performs. However you probably will not be able to manually control the transmission using the manual shift gate or paddle shifters.
Symptoms of a P2781 include:
- Manual shifting function via paddle shifters/manual shift gate will be disabled
- Failed downshift switch
- Wiring issue
- Shifter assembly failure
- ECU programming issue
How to Diagnose the Code?
The first step to figuring out what is causing a P2781 OBDII trouble code, is to check the condition of the wiring and connectors going to the shifter assembly. The manufacturer’s TSB (technical service bulletin) database is also a great resource for known problems and solutions. If nothing can be found, the downshift switch and possibly the shifter assembly itself will need to be tested.
What Repairs Will Fix P2781?
- Replace downshift switch
- Repair wiring/connectors
- Repair/replace shifter assembly
- Reflash/update ECU programming