Circuit Description
The powertrain control module (PCM) sends throttle position data to the transmission control module (TCM). The TCM uses this data to modify shift speeds. The data is sent to the TCM through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the PCM and TCM. A fault in the CAN will not cause DTC P0120 to set by itself. If a CAN fault occurs, other DTCs will set before DTC P0120.
When the TCM receives invalid throttle position data from the PCM, then DTC P0120 will set. DTC P0120 is a type A DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0120 Throttle Position (TP) Sensor Circuit
Conditions for Running the DTC
| • | The ignition voltage is 10.2-15.5 volts. |
| • | The engine speed is 400 RPM or greater. |
| • | No CAN DTC U0100. |
| • | Trans. protection mode is OFF. |
| • | The ignition is ON for 3 seconds or greater. |
Conditions for Setting the DTC
The PCM sends invalid throttle position data to the TCM for 4 seconds.
Action Taken When the DTC Sets
| • | The TCM requests the PCM to illuminate the malfunction indicator lamp (MIL). |
| • | The TCM uses the PCM default throttle position value for determining shift speeds. |
| • | The TCM turns the trans. protection mode ON. |
| • | The transmission will operate in 5th gear when the transmission is shifted into D range and 2nd gear when shifted into L range. |
| • | The line pressure is at maximum. |
| • | The torque converter clutch (TCC) is disabled. |
| • | The TCM freezes the transmission adaptive functions. |
| • | The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
| • | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records. |
| • | The TCM stores DTC P1791 in TCM history. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
| • | A scan tool can clear the MIL/DTC. |
| • | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
| • | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||
2 |
Important:
Did you record any PCM Failure Records? | Go to Step 3 | |||||
3 |
Did DTC P0120 reset? | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections | ||||
4 | Did any other DTCs set? | Go to Step 5 | |||||
5 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Is the action complete? | Go to Step 6 | -- | ||||
6 | Perform the following operation to verify the repair:
Does the DTC reset? | Go to Step 2 | Go to Step 7 | ||||
7 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | System OK |
