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Home >> Buick >> 2017 >> LaCrosse Base >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Automatic Transmission Range Select Lever >> Diagnostic Information and Procedures >> DTC P1787 or P17C8: Unexpected Range Change/Transmission Range Control Module Range Motor >> Circuit/System Description
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Circuit/System Description

The S3 Transmission Shift Lever will provide electrical signals based on customer input to the K38 Chassis Control Module, where the customer shift request will be determined. When the K38 Chassis Control Module receives the gear request signal from the S3 Transmission Shift Lever it sends the message for the K173 Transmission Range Control Module to engage the selected gear.