Circuit Description
The PCM uses TP, BARO, IAT and engine RPM to calculate an expected Mass Airflow rate. The PCM compares this value to the Mass Airflow value and the speed density calculation to verify proper throttle operation.
Conditions for Running the DTC
| • | DTCs P1515, P1516, P1517, P1518, not set. |
| • | DTCs P1120, P1220 and P1221 not set at the same time or DTCs P1120 and P1220 not set at the same time. |
| • | Engine operating longer than 1 second. |
| • | Engine speed greater than 500 RPM. |
Conditions for Setting the DTC
| • | The PCM detects that actual airflow (MAF) and Speed Density is much greater than the expected (calculated) airflow rate. |
| • | All above conditions met for less than 1 second. |
Action Taken When the DTC Sets
| • | The PCM will illuminate the MIL and the Reduced Engine Power light will be on when this diagnostic fails. |
| • | The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and/or Failure Records. |
| • | If no other TAC System DTCs are set, the TAC System will operate in Reduced Engine Power mode, and this DTC will be stored. If certain TAC System DTCs are set at the same time, the TAC System will either default to a more tightly restricted mode of operation if it is determined that limited safe operation is possible, or command engine shut down. |
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 History DTC will clear after forty consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | A last test failed (Current DTC) will clear when the diagnostic runs and does not fail. |
| • | PCM battery voltage is interrupted. |
| Important: The clear DTC info function may have to be performed twice in order to clear a Throttle Actuator Control System DTC. |
| • | Using a scan tool. |
Diagnostic Aids
| • | Inspect the throttle blade for being broken, bent or missing. |
| • | Inspect the TP sensor for proper installation. A sensor that is mis-aligned will set this DTC. |
| • | Refer to Intermittents under service category Symptoms . |
| • | If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Physically/visually inspect the throttle body assembly and correct any problems that you observe. Manually move the throttle blade from closed to Wide Open Throttle (WOT). You should not need to use excessive force. The throttle blade should move smoothly through the full range and should return to a slightly open position on its own.
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When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||||
2 | Is DTC P0101, P0102, P0103, P0107, P0108, P0112, P0113, P1111, or P1112 set? | -- | Diagnose these DTCs first | |||||||||
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Caution: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury. Important: If any of the conditions listed below exist, replace the throttle body. Inspect the throttle body for the following:
Did you find and correct the condition? | -- | Go to Diagnostic Aids | ||||||||||
4 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | ||||||||||
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 |
