With Manual Transmission

Steps 1-6:

Steps 7-14:

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 transmission and produces a pulsing voltage when 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.
If the PCM detects no vehicle speed for a specified length of time while other sensors indicate that the vehicle is moving, DTC P0502 sets. DTC P0502 is a type B DTC.

Conditions for Running the DTC
^ No Manifold Absolute Pressure (MAP) Sensor DTC's P0106, P0107 or P0108.
^ No Throttle Position (TP) Sensor DTC's P0121, P0122 or P0123.
^ Engine speed is 1,700 - 3,600 RPM.
^ Throttle position is less than 1 percent.
^ Engine vacuum is 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 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 at the time when the Conditions for Setting the DTC are met.
^ The PCM stores this information as Freeze Frame and Failure Records.
^ The PCM stores P0502 in PCM history.

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.
^ The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without an emission related diagnostic fault occurring.
^ A scan tool can clear the MIL/DTC.

Test Description
The numbers below refer to the step numbers on the diagnostic table.
5. The resistance measurement will not change if either the VSS high signal circuit or the VSS low signal circuit, but not both, is shorted to ground. The vehicle speed detector in the PCM and the VSS are matched in such a way that an open or a short to ground in the VSS low signal circuit will not usually cause a loss of speed signal or a DTC P0502 to set.
8. This step isolates the short between the VSS and the wiring.
10. The DMM will detect AC voltage if the VSS high signal circuit is shorted to ground.