P0854 Drive Switch Input Circuit Low

P0854 points to a low drive switch input circuit. The module sees a drive-range signal that is grounded, missing, or below expected value.

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 replace internal transmission components when the fault is still isolated to a low drive input signal.

Useful checks before replacing parts

Measure drive switch signal voltage, feed, ground, and continuity while moving the selector into and out of drive.
Inspect shifter or range switch adjustment, connector corrosion, rubbed wiring, short-to-ground faults, and water intrusion.
Compare drive input state with gear display, commanded range, starter inhibit, and any related range sensor codes.

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.