BI-Fuel/Alternative Fuels

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 Alternative Fuels ECM 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 below 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 Alternative Fuels ECM monitors a TP sensor signal voltage of less than 0.09 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 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 DESCRIPTION

Steps 1-10:

Steps 11-15:

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 low only when the throttle is opened.
6. This step determines if the TP sensor is the cause of the condition.
7. This step determines if the 5-volt reference circuit is the cause of the condition. The 4.8 volts is the minimum output that the gasoline Control Module should supply on the 5-volt reference circuit.