P162B

DTC P162B

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 P162B
- Remote Vehicle Speed Limiting Signal Message Counter Incorrect

Circuit/System Description

When a Slow-Down request is sent from OnStar(R) the vehicle communication interface module (VCIM) 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 a REDUCED ENGINE POWER indications is displayed. No DTCs will be set during this process.

The ECM monitoring the serial data message for specific validity traits. If the ECM determines that the validity of the message is in error DTC P162B will be set.

Conditions for Running the DTC

* The engine run time is greater than 5 seconds.
* No other serial data errors are present.

Conditions for Setting the DTC

* The VIN embedded in the Slow-Down serial data request does not match the VIN stored in the ECM.
* The rolling code counter embedded in the Slow-Down serial data request does not increment for 10 consecutive messages.

Action Taken When the DTC Sets

* ECM disregards all reduced vehicle speed request messages from the VCIM.
* The ECM stores DTC P162B in ECM 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.
* A scan tool clear DTC request is performed.

Reference Information
Description and Operation

Remote Vehicle Speed Limiting Description and Operation (Stolen Vehicle Slow-Down) (Remote Vehicle Speed Limiting)
Scan Tool Reference

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

Circuit/System Verification

If the DTC is set, perform the Stolen Vehicle Slow-Down Clear with a scan tool. If the DTC resets, replace the VCIM. If the DTC resets again, replace the ECM.

Repair Instructions

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

Control Module References (Programming and Relearning) for VCIM and ECM replacement, setup, and programming