Diagnostic Instructions
DTC Descriptor
DTC B0004 : Vehicle Speed Information Circuit Open
Circuit Description
The navigation radio receives the vehicle speed signal from the powertrain control module (PCM).
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 PCM to the GPS location signal. 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 PCM is unavailable.
The following symptoms may happen if the vehicle speed signal from the PCM is unavailable:
• | The vehicle icon may jump to different positions on the map screen. |
• | The 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 PCM. |
• | A history DTC clears after 50 ignition cycles without a vehicle speed signal failure. |
Reference Information
Schematic Reference
Navigation System Schematics
Connector End View Reference
Entertainment Connector End Views
Description and Operation
Navigation System Description and Operation
Electrical Information Reference
Scan Tool Reference
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. Connect a DMM to the vehicle speed signal (VSS) circuit terminal E and ground.
- 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 PCM. |
- If the circuit tests normal, replace the radio.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for radio and PCM replacement, setup, and programming