GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

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

DTC Descriptor

DTC B2461: Navigation ECU Synchronous Signal Error

Circuit Description

The circuitry is internal to the navigation radio. The Navigation ECU performs self diagnostics and sets the a DTC if any malfunctions are detected.

Conditions for Running the DTC

    â€¢ Radio ON.
    â€¢ Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The navigation radio has detected an internal ECU malfunction.

Action Taken When the DTC Sets

    â€¢ No map or blue screen appears on the display and index is not usable.
    â€¢ Navigation buttons do not function.

Conditions for Clearing the DTC

    â€¢ The condition responsible for setting the DTC no longer exists.
    â€¢ A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Navigation System Description and Operation

Electrical Information Reference

    â€¢  Circuit Testing
    â€¢  Connector Repairs
    â€¢  Testing for Intermittent Conditions and Poor Connections
    â€¢  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, with a scan tool clear all DTCs.
  2. Ignition ON, operate the navigation system within the Condition for Running the DTC.
  3. ⇒If the DTC resets, replace the radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for Radio replacement, setup, and programming