A transmission downshift switch allows you to manually change down the transmission gear using either the manual shift gate on the gear shift, or the paddle shifters located behind the steering wheel. If the downshift switch is not performing according to the preset parameters, a P2779 DTC will be stored.
How Serious is the Code?
The P2779 diagnostic trouble code is not serious enough to affect the drivability of your vehicle. However, you probably will not be able to downshift your transmission manually.
Symptoms of a P2779 include:
- Paddle shifters/manual shift gate will not work
- Failed downshift switch
- Wiring issue
- Shifter assembly failure
- ECU programming issue
How to Diagnose the Code?
The first step to diagnosing a P2779 OBDII trouble code, is to check the condition of the wiring and connectors going to the shifter assembly. The manufacturer’s TSB database should also be checked to see if there are any known causes and solution for this problem. If nothing is found, then the downshift switch and possibly the shifter assembly will need to be tested.
What Repairs Will Fix P2779?
- Replace downshift switch
- Repair wiring/connectors
- Repair/replace shifter assembly
- Reflash/update ECU programming