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 throttle angle that is greater than calculated, based upon engine speed and engine Manifold Absolute Pressure (MAP).

CONDITIONS FOR RUNNING THE DTC
^ The engine is operating on alternative fuel.
^ The engine has been operating for greater than 2 seconds.
^ No Alternative Fuel ECM DTCs are set. DTCs P1215, P1432, and P1433 may be set.
^ The engine MAP is less than 45 kPa.
^ The TP sensor angle has changed less than 2 percent for 2 seconds continuously.

CONDITIONS FOR SETTING THE DTC




The TP sensor angle is greater than the specified percentage at the given engine speed.

ACTION TAKEN WHEN THE DTC SETS
^ The Alternative Fuels ECM will illuminate the MIL and store the DTC as History during 1 drive trip in which 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 1-11:

Steps 12-19:

The numbers below refer to the step numbers on the diagnostic table.
5. This step indicates this sensor is currently functioning correctly. If you were sent to this diagnostic procedure from other service information, return to that procedure now.
6. This step isolates the signal circuit from the other possible causes of the DTC condition.
7. This step determines if the 5-volt reference circuit has the proper voltage. The amperage available on the 5-volt reference circuit should be about 180 mA.
8. This step determines if the signal circuit is shorted to voltage or open.
9. This step determines if the sensor ground circuit has good continuity. With the TP signal circuit (jumpered to 5 volts) grounded through the sensor ground circuit terminal, very little voltage should be available at the TP signal circuit.