DTC codes / P27xx · Transmission / P2781
P2781 indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the downshift switch circuit, which is part of the automatic transmission's manual shift control system. The switch is used to signal a downshift request, and a high voltage reading typically means the circuit is open, shorted to power, or the switch itself has failed.
Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.
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