P0855 Drive Switch Input Circuit High

P0855 indicates a high drive switch input circuit. The drive-range input is stuck high, open, or shorted to voltage compared with expected logic.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System: Transmission
Scope: iso-sae-controlled-p0
Standard: SAE J2012 / ISO 15031-6
Source: legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not treat a high drive switch input as a hydraulic engagement problem until the circuit is repaired.

Useful checks before replacing parts

Check drive switch signal voltage, ground integrity, connector fit, open circuits, short-to-voltage faults, and switch adjustment.
Compare scan-tool drive input status with actual shifter movement and range sensor data across all selector positions.
Inspect harness areas disturbed by shifter, console, or transmission service and verify the circuit under load.

Related OBD-II codes

These nearby transmission entries can help compare wording and fault area. They may share the same verification status as the source database.