P0500

DTC P0500 Vehicle Speed Sensor (VSS) Circuit:

Vehicle Speed Sensor (VSS):

CIRCUIT DESCRIPTION


The Engine Control Module (ECM) 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 ECM is toggled high and low. The ECM then converts 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 even though fuel has been cut for more than 5 seconds.


ACTION TAKEN WHEN THE DTC SETS


- The Malfunction Indicator Lamp (MIL) will illuminate.

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


CONDITIONS FOR CLEARING THE MIL/DTC

- The MIL will turn "OFF" after three consecutive drive cycles without a fault present.

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

- DTC(s) can be cleared by using a scan tool or by disconnecting the ECM battery feed.


DIAGNOSTIC AIDS


Check the following conditions:


- Poor connection at ECM. Inspect harness connectors for backed out terminal, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection.

- Damaged harness. Inspect the wiring harness for damage.

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

If DTC P0500 cannot be duplicated, the information included in the Freeze Frame data can be useful in determining vehicle operating conditions since the DTC was last set. This may assist in determining how often the DTC sets.

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


TEST DESCRIPTION


Number(s) below refer to the step number(s) on the Diagnostic Table.

1. The Engine 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. Check for the 5 volt reference signal from the ECM, the VSS is located behind the I/P cluster assembly.