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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 208 (Automatic Transmission - ALLISON - Diagnosis) >> Diagnostic Tests >> DTC P0731: Incorrect 1ST Gear Ratio >> Circuit Description

Circuit Description

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The Transmission Control Module (TCM) uses input from the turbine speed sensor and the output speed sensor to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current gear range.

This is a type "A" DTC.