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 B0004 00: Vehicle Speed Information Circuit OpenDiagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Vehicle Speed Signal | B0004 | B0004 | B0004 | B0004 |
Circuit Description
The navigation radio receives the vehicle speed signal from the engine control module (ECM).
Conditions for Running the DTC
| • | The navigation radio must detect a power mode transition to ON. |
| • | The vehicle must drive for 4 km (2.5 mi) after receiving a global positioning system (GPS) signal. |
Conditions for Setting the DTC
The navigation radio compares the vehicle speed signal from the ECM to the GPS location signal every second. If the GPS signal indicates that the vehicle has traveled 4 km (2.5 mi) but no vehicle speed signal was received, the radio sets the DTC.
Action Taken When the DTC Sets
The navigation radio uses the GPS signal when the vehicle speed signal from the ECM is unavailable.
The following symptoms may happen if the vehicle speed signal from the ECM is unavailable:
| • | The vehicle icon may jump to different positions on the map screen. |
| • | The vehicle icon, current position marker may not move on the map screen while the vehicle is being driven. |
| • | The route guidance accuracy may be degraded. |
Conditions for Clearing the DTC
| • | A current DTC clears when the navigation radio detects the vehicle speed signal from the ECM for more than 1 second. |
| • | A history DTC clears after 50 ignition cycles without a vehicle speed signal failure. |
Reference Information
Schematic Reference
Radio/Navigation System Schematics
Connector End View Reference
Description and Operation
Navigation System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Testing
Important: Diagnose any antilock brake system (ABS) related DTCs before performing this diagnostic.
- Ignition OFF, disconnect the X2 harness connector at the radio.
- 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 circuit tests normal, replace the radio.
| ⇒ | 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 ECM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for radio and ECM replacement, setup, and programming
