DTC P1761
Diagnostic Instructions
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 moving the gear lever, 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
The engine speed is greater than 400 RPM for
5 seconds.
Conditions for Setting the DTC
The 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. |
| • |
The TCM inhibits the Tap Up/Tap Down
function. |
| • |
The 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 for control solenoid valve
assembly information.
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- DTC P1761 is an informational DTC. Diagnose all
other BCM DTCs prior to DTC P1761. Refer to
Diagnostic Trouble Code (DTC) List - Vehicle .
- If there are no other body control DTCs, diagnosis is
accomplished by looking for an intermittent CAN circuit fault.
Refer to
Scan Tool Does Not Communicate with High Speed GMLAN Device
.
- 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 after completing the diagnostic
procedure.
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