P1761

DTC P1761

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1761
- Up and Down Shift Switch Signal Message Counter Incorrect

Circuit/System Description

A 12 volt ignition power circuit is provided by the body control module (BCM) to the Tap Up/Down circuit. When a Tap Up/Down request is made by pressing a plus (+) or minus (-) button or pressing the shift lever forward or rearward, a corresponding voltage drop occurs across the resistor network embedded in the switches. This voltage drop is monitored by the BCM through the signal circuit. The BCM sends the request to the transmission control module (TCM) to perform an upshift or downshift. The TCM is constantly monitoring the serial data sent from the BCM for the correct number and sequence of counts for Tap Up and Tap Down function.

Conditions for Running the DTC

Engine speed is greater than 400 RPM for 5 seconds.

Conditions for Setting the DTC

TCM detects the serial data rolling count value for the Tap Up/Tap Down does not match with the expected BCM count, 3 or greater times in 10 seconds.

Action Taken When the DTC Sets

* DTC P1761 is a Type C DTC.

* TCM inhibits the Tap Up Tap Down function.

* TCM inhibits manual shifting of forward gears.

Conditions for Clearing the DTC

DTC P1761 is a Type C DTC.

Reference Information

Description and Operation

Electronic Component Description Electronic Component Description for control solenoid valve assembly information.

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. DTC P1761 is an informational DTC. Diagnose all other BCM DTCs prior to DTC P1761.

• If other body control module DTCs are set
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

• If no other body control module DTCs are set
Diagnosis is accomplished by looking for an intermittent CAN circuit fault. Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device Scan Tool Does Not Communicate with High Speed GMLAN Device.

2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Control Module References Control Module References for BCM and control solenoid valve assembly replacement, programming and setup.

* Perform the Transmission Adaptive Values Learn Transmission Adaptive Values Learn following all transmission related repairs.