Description
This DTC detects a faulty throttle valve position. The throttle valve in the throttle body utilizes a throttle return spring to assist in positioning the throttle valve at a resting or default position. The powertrain control module (PCM) uses driver input from the accelerator pedal position (APP) sensor in order to calculate the desired throttle position. The PCM sends the desired throttle position or target value to the throttle actuator control (TAC) module. The TAC module achieves the desired throttle position by commanding the throttle control motor to position the throttle valve at the target value. The TAC module then compares the throttle position (TP) sensor 1 value to the target value. If necessary, the throttle control motor is moved slightly in order to obtain the exact target value position. If the TP sensor indicates that the throttle valve has failed to reach the default position a DTC P2112 sets. For additional information on the operation of the TAC system, refer to Throttle Actuator Control (TAC) System Description .
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P2112 Throttle Actuator Control (TAC) Throttle Valve-Stuck Closed
Conditions for Running the DTC
| • | The duty cycle of the open command for the TAC motor is at least 80 percent. |
| • | The TAC motor current is more than 2 amps. |
| • | DTC P2112 runs continuously once the above condition has been met. |
Conditions for Setting the DTC
The TP voltage does not change as expected when the throttle valve is commanded OPEN.
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL). |
| • | The PCM stores the conditions that were present when the DTC set as Freeze Frame data. |
| • | The engine will operate in the reduced power mode and the TP sensor angle will default to 19 percent. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the MIL on the third consecutive trip in which the diagnostic runs without a fault. |
| • | The PCM clears a History DTC after 40 consecutive warm-up cycles without a fault. |
| • | You use the scan tool Clear DTC Information function. |
Diagnostic Aids
| • | Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore causing the throttle valve not to close. Observe the Freeze Frame/Failure Records. |
| • | The throttle valve is spring loaded to a slightly open position. The throttle valve should be open approximately 11-15 percent. This is referred to as the rest position. |
| • | The throttle valve should not be completely closed or open any more than a specified amount. |
| • | The throttle valve should move open and to the closed position without binding under the normal spring pressure. |
| • | The throttle should NOT be free to move open or closed WITHOUT spring pressure. |
| • | For an intermittent condition, refer to Intermittent Conditions . |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | 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 | |
Are any other TAC system, TP sensor, or APP sensor DTCs also set? | Go to Step 3 | ||
3 |
Did the DTC fail this ignition? | Go to Step 5 | Go to Step 4 |
4 |
Did the DTC fail this ignition cycle? | Go to Step 5 | Go to Diagnostic Aids |
5 |
Did you find and correct the condition? | Go to Step 8 | Go to Step 6 |
6 |
Did you find and correct the condition? | Go to Step 8 | Go to Step 7 |
7 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | Go to Step 8 | -- |
8 |
Did the DTC fail this ignition? | Go to Step 2 | Go to Step 9 |
9 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |
