GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  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

    • Radio ON.
    • 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

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

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists.
    • 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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  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