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
Circuit/System Description
When the shift lever is placed left of the D position, the driver shift request (DSR), also known as the tap shift function, is activated. The DSR allows the vehicle operator to shift gears by pushing the shift lever forward for an upshift or pulling the shift lever rearward for a downshift. The BCM supplies battery voltage, ground and a signal circuit to the shift controller. The shift controller has Hall-effect switches connected to a resistor array. When the lever is left of the position, then pushed forward for an upshift, or pulled rearward for a downshift, a corresponding voltage drop occurs across the resistor network. This voltage drop is monitored by the BCM. The BCM will send the request to the transmission control module to perform the 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
* Tap Up and Tap Down message health is received from the BCM.
* Engine speed is 400 RPM or greater for 5 seconds.
Conditions for Setting the DTC
TCM detects an error in the rolling count value that does not match with the BCM count, 3 times within 10 seconds.
Action Taken When the DTC Sets
* DTC P1761 is a Type C DTC.
* TCM inhibits Tap Up/Down function.
* TCM inhibits manual shifting of forward gears.
Conditions for Clearing the DTC
DTC P1761 is a Type C DTC.
Reference Information
Schematic Reference
* Automatic Transmission Controls Schematics Electrical Diagrams
* Data Communication Schematics [1][2]Electrical Diagrams
* Body Control System Schematics [1][2]Body Control Systems
Connector End View Reference
* Component Connector End Views Fuel Pump and Level Sensor Assembly
* Inline Harness Connector End Views X102
Description and Operation
Electronic Component Description Electronic Component Description
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
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 body control module 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
2. Diagnosis is accomplished by looking for an intermittent CAN circuit fault. Refer to Scan Tool Does Not Communicate with Chassis High Speed GMLAN Device Scan Tool Does Not Communicate with Chassis High Speed GMLAN Device.
3. After performing the above steps, verify that the DTC does not reset by operating the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data. If the vehicle passes the Circuit/System Verification procedure, refer to Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections.
Repair Instructions
* Perform the Reset Transmission Adapts Reset Transmission Adapts following all transmission related repairs.
* Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.