Circuit Description
The Throttle Actuator Motor is a TAC controlled DC motor located on the throttle body. The motor drives the throttle plates. In order to decrease idle speed, the TAC commands the throttle closed reducing air flow into the engine and the idle speed decreases. In order to increase idle speed, the TAC commands the throttle plates open allowing more air to bypass the throttle plates. If the Actual idle RPM does not match the Desired idle RPM within a calibrated time, this DTC sets.
Conditions for Setting the DTC
| • | DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0171, P0172, P0174, P0175, P0300, P0441, P0443, P0500, P0502, P0503, P1120, P1220, P1221, P1441 not set. |
| • | Engine is operating for at least 60 seconds |
| • | ECT is greater than 60°C (140°F) |
| • | IAT is greater than -10°C (14°F) |
| • | Baro is greater than 65 kPa |
| • | System voltage is between 9.0 and 17.0 volts |
| • | Vehicle speed is less than 1 mph |
| • | APP Indicated Angle is 0% |
| • | Idle speed is above the desired RPM |
| • | Conditions exist for 5 seconds |
| • | The actual idle speed is 200 RPM greater than the desired idle speed |
Action Taken When the DTC Sets
| • | The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Use a scan tool in order to clear the MIL and the DTC. |
Diagnostic Aids
A build up of foreign material (ice) in the throttle bore may cause a high idle speed.
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can aid in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also aid determining how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This will isolate when the DTC failed. For an intermittent, refer to Symptoms
Test Description
The numbers below refer to the step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No | ||||
|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check ? | -- | ||||||
Does the engine speed correspond, within 200 RPM, with each command? | -- | Go to Diagnostic Aids | ||||||
3 | Is the Engine RPM greater than 200 RPM above Desired RPM? | -- | ||||||
4 | Check for the following conditions:
Is the action complete? | -- | -- | |||||
5 | Check for the following conditions:
Is the action complete? | -- | -- | |||||
6 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||
7 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |
