Circuit Description
The Throttle Actuator Motor is a TAC controlled DC motor located on the throttle body. The motor drives the throttle plates. To decrease idle speed, the TAC commands the throttle closed reducing air flow into the engine and the idle speed decreases. 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 will set .
Conditions for Setting the DTC
| • | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0171, P0172, P0174, P0175, P1120, P1220, and P1221 not set. |
| • | Engine running for at least 60 seconds |
| • | Engine coolant temperature greater than 60°C (140°F) |
| • | IAT greater than -10°C (14°F) |
| • | Baro greater than 65 kPa |
| • | System voltage between 9.0 and 17.0 volts |
| • | Vehicle speed less than 1 mph |
| • | APP Indicated Angle 0% |
| • | Idle speed below desired RPM |
| • | Conditions met for 5 seconds |
| • | The Actual idle speed is 75 RPM lower than the Desired idle speed |
Action Taken When the DTC Sets
| • | The PCM will illuminate the Malfunction Indicator Lamp (MIL) on the second consecutive drive trip that the diagnostic runs and fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. The first time the diagnostic fails, this information will be stored in Failure Records. If the diagnostic reports a failure on the second consecutive drive trip, the operating conditions at the time of failure will be written to Freeze Frame and the Failure record will be updated. |
Conditions for Clearing the MIL/DTC
| • | The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | A History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | PCM battery voltage is interrupted. |
| • | Using a Scan tool. |
Diagnostic Aids
Using Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If the DTC cannot be duplicated, the information included in the Freeze Frame and/or Failure Records data can be useful in determining how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that were noted. This will isolate when the DTC failed. For intermittents, 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 75 RPM, with each command? | -- | Go to Diagnostic Aids | ||||||
3 | Is the engine RPM greater than 75 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 |
