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.

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

Entertainment/Communication Connector End Views

Description and Operation

Navigation System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

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.

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

1. Ignition OFF, disconnect the X2 harness connector at the radio.
2. Ignition ON, operate the vehicle drive wheels at 5 mph. Test for 3-7 Hertz between the VSS circuit terminal E and ground.

⇒	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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for radio and ECM replacement, setup, and programming