BI-Fuel/Alternative Fuels

Schematic:

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor is a potentiometer. The gasoline Control Module (VCM / PCM or ECM) supplies about 5 volts on the TP sensor reference voltage circuit. The gasoline Control Module also supplies a ground circuit to the TP sensor. When the throttle is depressed the TP signal voltage rises to near the supplied 5 volts. As the throttle is released the TP signal voltage drops to around 0.6 volts. The gasoline Control Module and the AF ECU monitor the TP signal circuit voltage and determine the angle (or opening) of the throttle blade.

This DTC is used to indicate a TP sensor signal voltage that is above the normal operating range of the sensor.

CONDITIONS FOR RUNNING THE DTC
The engine is operating on alternative fuel.

CONDITIONS FOR SETTING THE DTC
The AF ECU monitors a TP sensor signal voltage of greater than 4.9 volts for at least 1 second 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 AF ECU will illuminate the MIL and store the DTC as History after TWO consecutive drive trips that the diagnostic runs and fails.
^ The AF ECU 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 AF ECU 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 ECU/VCM/PCM or ECM) power or ground MAY clear DTC Information. Clearing DTC Information with this method is inconsistent and should not be performed.

DIAGNOSTIC AIDS
Fault Not Present
Fault Not Present indicates the condition that caused the DTC to set is intermittent and not currently present. Refer to 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 the Diagnostic System Check - Alternative Fuels (Computers and Control Systems). Intermittent Conditions

TEST DESCRIPTION

Steps 1-11:

Steps 12-18:

The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the failure condition affects the gasoline control module.
3. This step determines if the failure condition is present.
4. This step determines if the TP signal is going high only when the throttle is opened.
6. This step determines if the TP signal circuit is the shorted condition.
7. This step determines if an open sensor ground condition is present.
8. This step determines if the 5-volt reference circuit is shorted to a voltage. The maximum output that the gasoline control module should supply on the 5 volt reference circuit is 5.2 volts.