P0500

Circuit Description
A processed Wheel Speed Sensor signal is sent from the Anti-lock Brake System Electronic Brake and Traction Control Module (EBTCM) controller to the Theft Deterrent Module. The signal is then sent from the Theft Deterrent Module to the Engine Control Module (ECM). The ECM calculates the vehicle speed from this signal. The vehicle speed/theft deterrent signal circuit is pulled up from B+ within the ECM. The circuit from the ABS controller to the Theft Deterrent Module is covered by the ABS controller diagnostics.

Conditions for Running the DTC
^ The fuel cut-off is enabled.
^ The engine speed is between 1800-2200 RPM.
^ The Engine Coolant Temperature (ECT) is greater than 65°C (149°F).

Conditions for Setting the DTC
The vehicle speed signal is less than 20 km/h (12 mph) for longer than 1 second.

Action Taken When the DTC Sets
The ECM turns on the Malfunction Indicator Lamp (MIL) and records the operating conditions in the Freeze Frame on the second consecutive drive trip that the diagnostic runs and fails.

Conditions for Clearing the MIL/DTC
^ The ECM turns off the MIL after three consecutive drive trips that the diagnostic runs and passes.
^ A History DTC clears after forty consecutive warm-up cycles in which no failures are reported by this diagnostic or any other emission related diagnostic.
^ The ECM battery voltage is interrupted.
^ The scan tool clears the MIL/DTC.

Diagnostic Aids

Notice: Refer to J 35616-A Connector Test Adapter Kit Notice in Service Precautions.

Use the J 35616-A Connector Test Adapter kit for any test that requires probing the ECM harness connector or a component harness connector.

Check for the following conditions:
^ Poor connections at the ECM or at the component-Inspect the harness connectors for the following conditions:
- Backed out terminals
- Improper mating
- Broken locks
- Improperly formed or damaged terminals
- Poor terminals to wire connections
^ A misrouted harness-Make sure that the harness is not routed too close to any high voltage wires such as the spark plug leads, or high current devices such as the alternator, the motors, the solenoids, etc.
^ A damaged harness-Inspect the wiring harness for any damage. If the harness appears to be OK, observe the scan tool while moving the related connectors and the wiring harnesses. A change in the display may reveal the location of the fault.

If the sensor signal is only affected when the harness is moved at a component, and there is no problem with the harness or the connections, the component may be damaged. Refer to Symptoms for assistance in diagnosing intermittent concerns. Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step verifies that the fault is currently present.
3. The test lamp connected to B+ is used to simulate the B+ pull-up within the ECM. The DMM can be connected to the shaft of the test lamp and battery ground. The momentary frequency signal verifies the initial communication between the theft deterrent system and the ECM.