Navigation System - Vehicle Position Indicator Inoperative or Erratic

Navigation System - Vehicle Position Indicator Inoperative or Erratic

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.

Circuit Description

The radio receives a vehicle speed signal from the electronic brake control module (EBCM) in order to correlate actual vehicle speed to the movement of the vehicle calculated by the navigation system and reported serial data. The vehicle speed signal also serves the purpose of updating the vehicle position indicator on the navigation screen.

Reference Information
Schematic Reference

Radio/Navigation System Schematics (Radio/Navigation System Schematics)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Navigation System Description and Operation (Navigation System Description and Operation)
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)

Scan Tool Reference

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

Circuit/System Verification

Radio ON, switch to the navigation screen on the radio. Drive the vehicle greater than 15 mph. Verify that the navigation screen shows that the vehicle is moving.

Circuit/System Testing

Important: Diagnose any antilock brake system (ABS) related DTCs before performing this diagnostic.

1. Ignition OFF, disconnect the radio harness connector X4. Connect a DMM to the vehicle speed signal (VSS) circuit terminal 5 and ground..
2. Ignition ON, operate the vehicle drive wheels at 5 mph. Verify 3-7 Hertz on the VSS circuit.

• If the reading is not as specified, test the VSS circuit for an open, high resistance, short to ground or short to voltage. If the circuit tests normal replace the EBCM.

3. If the circuit tests normal, replace the radio.

Repair Instructions

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

See Control Module References (Programming and Relearning) for Radio replacement, setup, and programming