Automatic Transmission - 4L80-E/4L85-E

DTC P1762

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.

DTC Descriptors
DTC P1762
- Transmission Mode Switch Signal Circuit

Circuit/System Description

The transmission mode switch signal enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the body control module (BCM) is momentarily toggled to 0 volts. This code sets when the rolling count of the transmission control module (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.
* The engine speed is between 500 and 6,500 RPM for 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 P1762 is a type C DTC.
* The TCM forces normal shift operation.

Conditions for Clearing the DTC

DTC P1762 is a type C DTC.

Reference Information
Schematic Reference

Automatic Transmission Controls Schematics (Diesel) (Electrical Diagrams)Automatic Transmission Controls Schematics (Gas) (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

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

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

Circuit/System Testing

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

If no communication with the BCM, refer to Control Module References (Programming and Relearning) for further diagnosis.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning) for TCM replacement, setup, and reprogramming.