B0004

DTC B0004

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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 Open

Circuit Description

The navigation radio receives the vehicle speed signal from the powertrain control module (PCM) through a dedicated circuit shared with the instrument panel cluster (IPC).

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 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 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 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 PCM for more than 1 second.
* A history DTC clears after 50 ignition cycles without a vehicle speed signal failure.

Diagnostic Aids

A short to voltage or ground in the vehicle speed circuit will cause an IPC speedometer problem also. Make sure there are no IPC speedometer concerns.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X2 at the radio. Disconnect the harness connector X1 at the instrument panel cluster.
2. Test for less than 5 ohms on the vehicle speed signal between the radio harness connector X2 terminal E and the IPC connector X1 terminal 21.

^ If less than the specified range, repair the open/high resistance. If the circuit tests normal, replace the radio.

Repair Instructions

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

* Inside Rearview Mirror Replacement