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 Circuit

Circuit/System Description

The driver shift request (DSR), also known as the TAP Up/Downshift manual shift function, allows the driver to select the desired range of gears for current driving conditions. The DSR shift system is activated when the gear selector is in the manual position. The DSR system is deactivated in all other range positions. When DSR is selected, a signal is sent to the body control module (BCM) and the also to the transmission control module (TCM). Each time a signal is sent, an internal counter in the BCM and TCM increments. Both counters must have the same value. This code sets when the rolling count value of the TCM does not match the same rolling count 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 (6L45/6L50/6L80/6L90 - Automatic Transmission)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Description and Operation

Electronic Component Description (Electronic Component Description)
DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

Note: If other DTCs are set, diagnose those DTCs first.

1. Ignition ON, verify with a scan tool the Tap Up/Down Switch parameter displays ON in the Chassis Data list under BCM.
2. Ignition ON, verify with a scan tool the Tap Up/Down parameter displays UP when pressing the plus (+) switch and Down when pressing the minus (-) switch.
3. Ignition ON, verify with a scan tool the Driver Shift Control parameter in the Transmission Data list changes from, Inactive to Active when placing the automatic transmission shift lever in manual mode position.
4. Ignition ON, verify with a scan tool the Driver Shift Request Switch 1 displays NONE in the transmission data list.
5. Ignition ON, verify with a scan tool the Driver Shift Request Switch 1 displays Upshift when pressing the plus (+) switch and Downshift when pressing the minus (-) switch.
6. 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.

Circuit/System Testing

If no other DTCs are set, diagnosis is accomplished by testing for a condition on the CAN circuit. Refer to Scan Tool Does Not Communicate with High Speed GMLAN Device (Scan Tool Does Not Communicate with High Speed GMLAN Device).

Repair Instructions

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

Control Module References (Programming and Relearning)for control solenoid (W/body and TCM) valve assembly replacement, setup, and programming.