Fault Family System: Powertrain (P-Codes) 19 SAE Codes

Transmission Mode Switch Circuit

Diagnostic & Technical Explanation

Code P071A (Transmission Mode Switch A Circuit) sets when the TCM sees an open, shorted, or implausible signal from one of several driver-selectable transmission mode switches (e.g., normal/performance, winter, manual-select gate). Causes are worn switch contacts, a stuck detent, or chafed wiring at the shifter assembly.

These 19 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 19 times.

Codes in this family (19)

Code	Definition	Repair coverage
P071A	Transmission Mode Switch A Circuit	3 ranked fixes
P071B	Transmission Mode Switch A Circuit Low	3 ranked fixes
P071C	Transmission Mode Switch A Circuit High	3 ranked fixes
P071D	Transmission Mode Switch B Circuit	3 ranked fixes
P071E	Transmission Mode Switch B Circuit Low	3 ranked fixes
P071F	Transmission Mode Switch B Circuit High	3 ranked fixes
P078F	Transmission Mode Switch C Circuit	3 ranked fixes
P0790	Normal/Performance Switch Circuit	3 ranked fixes
P07CC	Transmission Mode Switch C Circuit Low	3 ranked fixes
P07CD	Transmission Mode Switch C Circuit High	3 ranked fixes
P07CE	Transmission Mode Switch D Circuit	3 ranked fixes
P07CF	Transmission Mode Switch D Circuit Low	3 ranked fixes
P07D0	Transmission Mode Switch D Circuit High	3 ranked fixes
P07D1	Transmission Mode Switch E Circuit	3 ranked fixes
P07D2	Transmission Mode Switch E Circuit Low	3 ranked fixes
P07D3	Transmission Mode Switch E Circuit High	3 ranked fixes
P07D4	Transmission Mode Switch F Circuit	3 ranked fixes
P07D5	Transmission Mode Switch F Circuit Low	3 ranked fixes
P07D6	Transmission Mode Switch F 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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