P0500

Diagnostic Chart:

Wiring Diagram:

Circuit Description

The Powertrain Control Module (PCM) supplies 5 volts to the Vehicle Speed Sensor (VSS). While the vehicle is moving, the reed switch within the VSS will open and close four times per each revolution of the speedometer cable. Because the reed switch opens and closes, the voltage at the PCM is toggled high and low. The PCM then convents this toggled high/low voltage into a vehicle speed that is displayed in km/h and mph.

Conditions for Setting the DTC

No vehicle speed sensor signal, fuel shut off mode for more than 4 seconds.

Action Taken When the DTC Sets

^ The Malfunction Indicator Lamp (MIL) will illuminate.

^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame buffer.

^ The PCM will enter the Fail-Safe Function and stop Idle Speed (ISC) control.

Conditions for Clearing the MIL/DTC

^ The MIL will turn OFF after three consecutively passing cycles without a fault present.

^ A History DTC will clear after 40 consecutive warm-up cycles without a fault.

^ DTCs can be cleared by using a scan tool or by disconnecting the PCM battery feed.

Diagnostic Aids

Check for any of the following conditions:

^ A poor connection at the PCM. Inspect the harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and a poor terminal to wire connection.

^ A damaged wiring harness. Inspect the wiring harness for damage and repair as necessary.

^ A faulty speedometer cable. If the speedometer cable is binding, a false DTC P0500 can be set. Make sure that the speedometer cable is free from any restrictions and that it has a secure connection to the I/P cluster assembly.

If a DTC P0500 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions when the DTC was first set.

If any wiring repairs need to be made, Refer to Repair Procedures in Electrical Diagrams.

Test Description

The numbers below refer to the step numbers in the Diagnostic Table.

1. The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame data on the scan tool if applicable.

This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.

2. Determine if fault is present.

3. Review Freeze Frame data to determine when the DTC set. Always record this information.

4. Checks for the 5 volt reference signal from the PCM. The VSS is located behind the I/P cluster assembly.