P0500

CIRCUIT DESCRIPTION
The vehicle speed output signal is generated by the gasoline Control Module (VCM/PCM or ECM). The signal is a duplicate of the Vehicle Speed Sensor (VSS) signal that the gasoline Control Module receives from the VSS. The gasoline Control Module (VCM/PCM or ECM) contains an integrated circuit called a driver that switches the signal circuit to ground at a rate of 4,000 pulses for every km/h (mph) the vehicle is driven. Various modules (IP, Cruise, Alternative Fuels ECM, etc.) that are connected to the vehicle speed output circuit convert the 4K PPM into a vehicle speed value.

This DTC is used to indicate that the Alternative Fuels ECM cannot monitor an accurate vehicle speed.

CONDITIONS FOR RUNNING THE DTC
The engine is operating on Alternative Fuel.

CONDITIONS FOR SETTING THE DTC
The Alternative Fuels ECM monitors a vehicle speed output signal circuit fault.

ACTION TAKEN WHEN THE DTC SETS
^ A first failure of this DTC will NOT illuminate the MIL and will store as Last Test Failed but not as History.
^ The Alternative Fuels ECM will illuminate the MIL and store the DTC as History after 2 consecutive drive trips that the diagnostic runs and fails.
^ The Alternative Fuels ECM will record operating conditions at the time the DTC sets. This information will be stored as Freeze Frame data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The Last Test Failed status will clear when the DTC runs and passes.
^ The Alternative Fuels ECM will turn OFF the MIL after 3 consecutive drive trips that the DTC runs and passes.
^ The History status will clear after 40 consecutive WARM-UP cycles with NO failures of ANY DTC.
^ All DTC Information can be cleared using a scan tool.
^ Interruption of Control Module (AF ECM/VCM/PCM or ECM) power or ground MAY clear DTC Information. Clearing DTC Information with this method is in-consistent and should not be performed.

DIAGNOSTIC AIDS

Intermittent Condition
A fault not present indicates the condition that caused the DTC to set is intermittent and not currently present. Refer to the Intermittent Conditions diagnostic information located in Symptoms - Computers and Control Systems. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in Diagnostic System Check - Alternative Fuels (Computers and Control Systems). Initial Inspection and Diagnostic Overview Intermittent Conditions

TEST

Steps 1-7: