Circuit Description
The throttle actuator (TAC) motor is controlled by the TAC module, using various inputs from the powertrain control module (PCM) which are communicated across serial data. The DC motor located on the throttle body drives the throttle plate. In order to decrease idle speed, the TAC module commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the TAC module commands the throttle plate open allowing more air to bypass the throttle plate. If the actual idle RPM does not match the desired idle RPM within a calibrated time, this DTC sets.
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0171, P0172, P0174, P0175, P0200-P0206, P0300, P0336, P0401, P0403, P0404, P0405, P0502, P0503, P1112, P1114, P1115, P1120, P1220, P1221, P1374, P1380, or P1381 are not set: |
| • | The engine is operating for at least 2 minutes. |
| • | The engine coolant temperature (ECT) is more than -40°C (-40°F). |
| • | The intake air temperature (IAT) is more than -40°C (-40°F). |
| • | The barometric pressure (BARO) is more than 65 kPa. |
| • | The system voltage is between 9-18 volts. |
| • | The vehicle speed is less than 4.8 km/h (3 mph). |
| • | The accelerator pedal position (APP) indicated angle is less than 0.25 percent. |
Conditions for Setting the DTC
| • | The actual idle speed is approximately 150 RPM lower than the desired idle speed. |
| • | All above conditions are present for 15 seconds. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. |
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. |
Diagnostic Aids
If the condition is intermittent, refer to Intermittent Conditions .
Test Description
The number below refers to the step number on the diagnostic table.
Step | Action | Yes | No | ||||
|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | |||||||
1 | Did you perform the Diagnostic System Check-Engine Control? | Go to Step 2 | |||||
Does the engine speed correspond, within 100 RPM, with each command? | Go to Diagnostic Aids | Go to Step 3 | |||||
3 | Is the engine RPM more than 100 RPM more than or less than the Desired RPM? | Go to Step 4 | Go to Step 5 | ||||
4 | Inspect for the following conditions:
Did you complete the repair? | Go to Step 6 | -- | ||||
5 | Inspect for the following conditions:
Did you complete the repair? | Go to Step 6 | -- | ||||
6 |
Does the DTC reset? | Go to Step 2 | Go to Step 7 | ||||
7 | Does the scan tool indicated any DTCs set that you have not diagnosed? | System OK | |||||
