P0193

DTC P0193

Circuit Description

The fuel rail pressure (FRP) sensor is a pressure sensor. The alternative fuels engine control module (ECM) supplies about 5 volts on the FRP sensor reference voltage circuit. The alternative fuels ECM also supplies a ground circuit to the FRP sensor. When the fuel rail pressure is normal, the FRP signal voltage rises to near 2.5 volts. If the fuel rail pressure increases, the MAP signal voltage increases. The alternative fuels ECM monitors the FRP signal circuit voltage in order to determine the correct fuel injector pulse width modulation.


This DTC sets when the FRP sensor signal voltage is more than the normal operating range of the sensor.


Conditions for Running the DTC

* The engine speed is greater than 100 RPM.
* alternative fuels ECM DTC P0336 is not set.



Conditions for Setting the DTC

The alternative fuels ECM monitors a FRP sensor signal voltage of more than 4.95 volts for at least 10 seconds continuously.


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 with a scan tool.



Test Description

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the condition is present.
4. This step determines if an open sensor ground circuit condition is present. The FRP, FRT, FTP and FTT share a sensor ground. An open circuit between the splice and the alternative fuels ECM will cause all signal circuits to indicate high voltage.
5. This step determines if an open or shorted signal circuit is the cause of the condition.
6. This step determines if a shorted 5-volt reference circuit is the cause of the condition.
7. This step determines if an open sensor ground circuit between the harness connector of the FRP sensor and the splice is the cause of the condition.