Circuit Description
The throttle body assembly contains the following components:
| • | The throttle blade |
| • | The throttle actuator motor |
| • | The throttle position (TP) sensor 1 and 2 |
| • | The throttle actuator control (TAC) module |
The TAC system monitors the throttle position with 2 sensors. If the powertrain control module (PCM) receives a message from the TAC module that indicates one of the following conditions, DTC P0120 will set:
| • | The TP sensor 1 voltage is outside a predetermined range. |
| • | The reference voltage is out of range. |
| • | An improper throttle blade minimum position was learned. |
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0120 Throttle Position (TP) Sensor 1 Circuit
Conditions for Running the DTC
| • | DTCs P0606, P2107, P2108 are not set. |
| • | The Ignition 1 Signal parameter is in the crank or the run position. |
| • | The ignition voltage is more than 5.23 volts. |
| • | The communications between the TAC module and the PCM must be valid. |
Conditions for Setting the DTC
| • | The TP sensor 1 voltage is continuously less than 0.376 volts or more than 4.506 volts for longer than 100 ms. |
| OR |
| • | The PCM learns a minimum throttle position of more than 0.714 volts. |
| This occurs once per ignition cycle at power-up. |
| OR |
| • | The TP sensor reference voltage is less than 4.54 volts for longer than 10 ms, or more than 5.21 volts for longer than 1 second. This test occurs continuously. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the scan tool indicate voltage within the specified range? | 1.1-1.5 V | Go to Step 3 | Go to Step 5 |
3 | Fully depress the accelerator pedal. Does the scan tool indicate the voltage is within the specified values? | 3.7-4.2 V | Go to Step 4 | Go to Step 5 |
4 |
Did this DTC fail this ignition? | -- | Go to Step 5 | Go to Testing for Intermittent Conditions and Poor Connections |
5 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 6 | -- |
6 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 7 |
7 |
Important: Be aware that repairing one individual condition may correct more than one DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |
