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 more 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 for additional information. If any additional DTCs were stored proceed to the applicable DTC table in the order stated in the OBD System Check.
Test Description
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 high only when the throttle is opened.
-
This step determines if the TP signal circuit is the shorted condition.
-
This step determines if an open sensor ground condition is present.
-
This step determines if the 5 volt reference circuit is shorted to a voltage. 5.2 volts is the maximum output that the gasoline control module should supply on the 5 volt reference circuit.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the AF Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Alternative Fuels (AF) Powertrain On Board (OBD) System Check | |
Does the TP Sensor data parameter indicate TP voltage greater than the specified value? | 4.8 V | |||
Does the TP sensor data parameter indicate TP voltage greater than the specified value? | 4.8 V | |||
Open and close the throttle while observing the TP sensor data parameter. Does the TP sensor data parameter ever indicate TP voltage greater than the specified value? | 4.8 V | |||
5 | The fault is not present. Refer to Diagnostic Aids. Are any DTC's stored that have not been diagnosed? | -- | Go to the Diagnostic Trouble Code (DTC) List | Go to Intermittent Conditions |
Does the TP sensor data parameter indicate TP voltage LESS than the specified value? | 0.75 V | |||
Connect the J 35616-200 Un-powered Test Lamp between the sensor ground circuit terminal and BATTERY POSITIVE. Is the test lamp illuminated? | -- | |||
Is the voltage LESS than the voltage specified? | 5.2 V | |||
9 |
The 5 volt reference circuits (A and B) are shared within the VCM. The short may be located on either of the 5 volt reference circuits that the VCM provides. Disconnect the AF ECU connector that contains the 5 volt reference circuit in order to determine if the AF ECU is the cause of the short to voltage. Was a wiring repair made? | -- | ||
10 |
Was a wiring or terminal repair necessary? | -- | ||
11 |
Disconnect the AF ECU connector that contains the TP signal circuit in order to determine if the AF ECU is the cause of the short to voltage. Was a wiring repair made? | -- | ||
12 |
Is TP signal circuit continuity indicated? | -- | ||
13 | Repair the open TP signal circuit between the TP signal circuit splice and the AF ECU. Is the circuit repair complete? | -- | -- | |
14 |
Was a terminal repair made? | -- | ||
15 | Replace the TP Sensor. Refer to Throttle Position Sensor Replacement in the Engine Controls section of the gasoline service manual. Is the replacement complete? | -- | -- | |
16 |
Important: The following control module replacement procedures must all be completed before attempting to operate the vehicle.
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. All of the above procedures are located in the gasoline service manual. Is the replacement complete? | -- | -- | |
17 | Replace the AF ECU. Refer to Engine Control Unit Replacement . Is the replacement complete? | -- | -- | |
18 |
Did this DTC RUN and PASS? | -- | System OK |
