GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1761: Up and Down Shift Switch Signal Circuit

Circuit/System Description

The TAP Shift Switch Signal system allows the driver to manually shift gears by using the Upshift and Downshift positions located on the automatic transmission shift Lever. When TAP mode is selected, the shift switch input signals to the body control module (BCM). This code sets when the rolling count of the TCM does not match the same value sent from the BCM.

Conditions for Running the DTC

The engine run time is greater than 5 seconds.

Conditions for Setting the DTC

The TCM detects an error in the rolling count value that does not match with the BCM.

Action Taken When the DTC Sets

    • DTC P1761 is a Type C DTC.
    • The TCM disables TAP Shift operation.

Conditions for Clearing the DTC

DTC P1761 is a Type C DTC.

Reference Information

Schematic Reference

Automatic Transmission Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Transmission General Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Transmission Control Module Scan Tool Information

Circuit/System Testing

Ignition ON, attempt to establish communication with the BCM with a scan tool.

If no communication with the BCM, refer to Control Module References for further diagnosis.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for TCM replacement, setup, and programming.