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.
The engine is operating on alternative fuel.
The Alternative Fuels ECM monitors a TP sensor signal voltage of less than 0.09 volts for at least 1 second continuously.
• | 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. |
• | 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. |
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 - Engine Controls. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in Diagnostic System Check - Alternative Fuels (Engine Controls) .
The numbers below refer to the step numbers on the diagnostic table.
This step determines if the failure condition affects the gasoline Control module.
This step determines if the failure condition is present.
This step determines if the TP signal is going low only when the throttle is opened.
This step determines if the TP sensor is the cause of the condition.
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.
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Did you perform the Alternative Fuels Engine Controls Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Alternative Fuels (Engine Controls) |
Does the TP sensor data parameter indicate TP voltage less than the specified value? | 0.09 V | Go to Step 6 | Go to Step 3 | |
Does the TP sensor data parameter indicate TP voltage less than the specified value? | 0.09 V | Go to Step 14 | Go to Step 4 | |
Open and close the throttle while observing the TP Sensor data parameter. Does the TP sensor data parameter ever indicate TP voltage less than the specified value? | 0.09 V | Go to Step 6 | Go to Step 5 | |
5 | The fault is not present. Refer to Diagnostic Aids. Are any DTCs stored that have not been diagnosed? | -- | Go to Intermittent Conditions | |
Does the TP sensor data parameter indicate TP voltage GREATER than the specified value? | 4.8 V | Go to Step 12 | Go to Step 7 | |
Is the voltage LESS than the value specified? | 4.8 V | Go to Step 10 | Go to Step 8 | |
8 |
Was a wiring repair made? | -- | Go to Step 15 | Go to Step 9 |
9 |
Was a wiring repair made? | -- | Go to Step 15 | Go to Step 13 |
10 |
Was a wiring or terminal repair necessary? | -- | Go to Step 15 | Go to Step 11 |
11 |
Some 5-volt reference circuits are shared within the PCM. The short may be located on either of the 5-volt reference circuits that the PCM provides. Was a repair made? | -- | Go to Step 15 | Go to Step 13 |
12 | Replace the TP Sensor. Refer to Throttle Position Sensor Replacement in the Engine Controls section of the G Van Service Manual. Is the replacement complete? | -- | Go to Step 15 | -- |
13 |
Important: The following Control Module replacement procedures must all be completed before attempting to operate the vehicle. The following procedures are located in the G Van Service Manual.
Important: In order to perform the variation learn procedure, a switch-over to gasoline operation is necessary. Remove the CNG 20-amp fuse in order to perform the switch-over. Is the replacement complete? | -- | Go to Step 15 | -- |
14 |
Is the replacement complete? | -- | Go to Step 15 | -- |
15 |
Did this DTC run and pass? | -- | System OK | Go to Step 2 |