Speed Compensated Volume Malfunction

Speed Compensated Volume Malfunction

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.

Circuit Description

The vehicle speed signal circuit from the electronic brake control module (EBCM) to the radio provides vehicle speed information to the radio for the purpose of raising or lowering the radio volume based on the vehicle speed. The radio increases volume as the vehicle speed increases to account for road noise. This feature is called Speed Compensated Volume (SCV)

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, Turn the SCV control to high, drive the vehicle at various speeds and verify that the radio maintains a comfortable listening level at different speeds.

Circuit/System Testing

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