With Manual Transmission

DTC P0502

Circuit Description
Vehicle speed information is provided to the Powertrain Control Module (PCM) by the Vehicle Speed Sensor (VSS). The VSS is a permanent magnet generator that is mounted on the transaxle and produces a pulsing voltage whenever vehicle speed is over 5 km/h (3 mph). The AC voltage amplitude and frequency increases with vehicle speed. The PCM converts the pulsing voltage into km/h (mph). The PCM supplies the necessary signal to the instrument panel for speedometer odometer operation and to the cruise control and multi-function alarm module.

Conditions for Running the DTC
^ Engine speed is 1,900 - 3,800 RPM.
^ Throttle position is 0-1 percent.
^ Engine vacuum, 70 - 80 kPa (10 - 12 psi).
^ The above conditions are met for 5 seconds.

Conditions for Setting the DTC
Vehicle speed is less than 3 km/h (2 mph).

Action Taken When the DTC Sets
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive drive trip in which the Conditions for Setting the DTC are met.
^ The PCM disables Cruise Control.
^ The PCM commands the coolant fan ON.
^ The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores DTC P0502 in PCM history during the second consecutive trip in which the Conditions for Setting the DTC are met.

Conditions for Clearing the MIL/DTC
^ The PCM turns OFF the MIL during the third consecutive trip in which the diagnostic test runs and passes.
^ The PCM cancels the DTC default actions when the fault no longer exists and the DTC passes.
^ A scan tool can clear the MIL/DTC.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring.

Diagnostic Aids
Ensure the VSS is correctly torqued to the transmission housing.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step tests the ability of the VSS to produce an AC voltage. This step also verifies the integrity of the wiring to the PCM.
4. This step tests the VSS circuit for correct resistance.

Steps 1-9:

Steps 10-16:

DTC P0502