P162B

DTC P162B

Diagnostic Instructions

- Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure, Diagnostic System Check - Vehicle
- Review Strategy Based Diagnosis for an overview of the diagnostic approach, Strategy Based Diagnosis
- Diagnostic Procedure Instructions provides an overview of each diagnostic category, Diagnostic Procedure Instructions

DTC Descriptor

DTC P162B: Remote Vehicle Speed Limiting Signal Message Counter Incorrect

Circuit/System Description

When a remote slow-down request is sent from OnStar, the vehicle communication interface module sends a serial data message to the engine control module (ECM) indicating that reduced vehicle speed has been requested. Once the request is active, the ECM begins reducing engine torque to match requested vehicle speed and the REDUCED ENGINE POWER message is displayed.

Conditions for Running the DTC

- The engine run time is greater than 5 seconds.
- A remote slow-down request is sent from OnStar

Conditions for Setting the DTC

- The VIN embedded in the slow-down request does not match the VIN stored in the ECM.
- The rolling code counter embedded in the slow-down request does not increment for ten consecutive messages.

Action Taken When the DTC Sets

- ECM ignores all reduced vehicle speed request messages from the vehicle communication interface module.
- The ECM stores DTC?P162B in history.

Conditions for Clearing the DTC

- The condition responsible for setting the DTC no longer exists.
- A history DTC will clear after 40 malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference
OnStar Schematics, OnStar Schematics

Description and Operation
Remote Vehicle Speed Limiting Description and Operation, Remote Vehicle Speed Limiting

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

Scan Tool Reference
Control Module References for scan tool information, Control Module References

Circuit/System Verification

Perform the scan tool Stolen Vehicle Slow-Down Clear. Verify DTC P162B is not set.
-> If the DTC is set, replace the vehicle communication interface module and retest. If the DTC sets again, replace the ECM.

Repair Instructions

- Perform the Diagnostic Repair Verification after completing the repair, Verification Tests
- Control Module References for vehicle communication interface module and ECM replacement, setup, and programming, Control Module References