Fault Family System: Powertrain (P-Codes) 9 SAE Codes

Park Neutral Drive Switch Circuit

Diagnostic & Technical Explanation

Code P081C (Park Input Circuit) sets when the ECM/TCM sees an open, shorted, or implausible signal from a discrete Park, Neutral, or Drive position switch used for start interlock and backup-lamp control. Causes are a maladjusted or worn switch at the shift shaft, a corroded connector, or chafed wiring at the transmission case.

These 9 diagnostic trouble codes share one detection mechanism and one repair path, which is why MechanicDB groups them into a single authored fault family rather than repeating the same explanation 9 times.

Codes in this family (9)

Code	Definition	Repair coverage
P081C	Park Input Circuit	3 ranked fixes
P081D	Neutral Input Circuit	3 ranked fixes
P084F	Park/Neutral Switch Output Circuit	3 ranked fixes
P0850	Park/Neutral Switch Input Circuit	3 ranked fixes
P0851	Park/Neutral Switch Input Circuit Low	3 ranked fixes
P0852	Park/Neutral Switch Input Circuit High	3 ranked fixes
P0853	Drive Switch Input Circuit	3 ranked fixes
P0854	Drive Switch Input Circuit Low	3 ranked fixes
P0855	Drive Switch Input Circuit High	3 ranked fixes

What this page does not show

This page publishes the fault mechanism and the code index. The licensed dataset adds, for every one of the 15,886 codes, the full authored repair set (56,729 procedures in total) with the fields deliberately withheld here:

Procedures 2..n after the first-listed procedure
Aftermarket parts cost ranges in USD (est_parts_cost_min/max_usd)
Professional labor-hour estimates (est_labor_hours)
Step-by-step diagnostic and repair instructions
Replacement-part mappings and catalog lookups
6,637 manufacturer-specific OEM codes across 32 makes ($149 tier)

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