Code Definition

P1781 — Transmission switch lever switch fault

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Toyota

About P1781

P1781 is a manufacturer-specific powertrain diagnostic trouble code recorded for Toyota vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1781 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

On some Toyota systems the shift lever carries its own position switch, separate from the transmission range switch, that sends discrete signals to the Transmission Control Module or Body ECU to indicate the selected gear such as Park, Reverse, Neutral, or Drive. The module reads the combination of these switch contacts to know the lever position for shift control and related functions. DTC P1781 sets when the module detects a malfunction in the shift lever switch circuit, such as a missing input, a contradictory combination, or a voltage out of the expected range during selection. With this f...

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