Circuit Description
The powertrain control module (PCM) uses the following components in order to calculate the predicted mass airflow (MAF) rate:
| • | The throttle position (TP) |
| • | The barometric pressure (BARO) |
| • | The intake air temperature (IAT) |
| • | The engine RPM |
The PCM compares the predicted MAF value to the actual MAF value and to the speed density calculation in order to verify the proper throttle operation.
Conditions for Running the DTC
| • | DTCs P0601, P0602, P0604, P0606, P1515, P1516, P1517, or P1518 are not set. |
| • | DTCs P1120, P1220, and P1221 are not set at the same time, or DTCs P1120 and P1220 are not set at the same time. |
| • | The engine operates longer than 1 second. |
| • | The engine speed is greater than 500 RPM. |
Conditions for Setting the DTC
| • | The PCM detects that the difference between the actual airflow and the speed density calculated airflow is greater than expected. |
| • | All of the above conditions are met for less than 1 second. |
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records. |
| • | The control module commands the TAC system to operate in the Reduced Engine Power mode. |
| • | A message center or an indicator displays Reduced Engine Power. |
| • | Under certain conditions the control module commands the engine OFF. |
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
| • | Inspect the throttle blade for damage such as broken edges, bent blade, or missing pieces. |
| • | Inspect the TP sensor for proper installation. A sensor that is mis-aligned could set this DTC. |
| • | Inspect the TAC module connectors for signs of water intrusion. When this condition occurs, multiple DTCs could be set without circuit or component conditions found during diagnostic testing. |
| • | 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 excess force. The throttle blade should move smoothly through the full range and should return to a slightly open position naturally. |
| • | When the TAC module detects a condition within the TAC system, more than 1 TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Disconnecting components during testing may set additional DTCs. Be aware of this condition if you review the stored information in Capture Info. |
| • | For an intermittent condition, 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 Controls? | Go to Step 2 | |||||||||
2 | Is DTC P0101, P0102, P0103, P0107, P0108, P0112, P0113, P1111, or P1112 set? | Go to Step 3 | |||||||||
3 |
Important: If any of the conditions listed below exist, replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Inspect the throttle body for the following conditions:
Did you find and correct the condition? | Go to Step 4 | Go to Diagnostic Aids | ||||||||
4 |
Does the DTC run and pass? | Go to Step 5 | Go to Step 2 | ||||||||
Use a scan tool in order to observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | System OK | ||||||||||
