P0955 Auto Shift Manual Mode Circuit

P0955 indicates an auto shift manual mode circuit fault. The module cannot reliably identify or enter the manual shift mode request state.

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 diagnose shift timing until the manual mode enable circuit is confirmed.

Useful checks before replacing parts

Compare manual mode switch data with actual selector position, upshift and downshift inputs, range data, and gear display behavior.
Inspect mode switch wiring, shifter connector fit, spilled-liquid damage, reference voltage, ground, and module communication data.
Check whether the issue affects mode entry only, individual shift requests, or the display of selected gear.

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.