Circuit Description
The actual throttle position is compared to an expected throttle position based on engine load. The powertrain control module (PCM) determines engine load based on inputs from the mass air flow (MAF) sensor and the manifold absolute pressure (MAP) sensor. Further comparisons are done to distinguish if a sensor is at fault, and the respective DTC will set. If the PCM detects that the current load and throttle position are not consistent with the expected load and throttle position, DTC P0068 will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0068 Throttle Body Airflow Performance
Conditions for Running the DTC
| • | DTCs P0120, P0220, P0601, P0604, P0606, P1125, P1516, P2101, P2107, P2108, P2119, P2120, P2125, P2135, P2138, U0107 are not set. |
| • | The Engine Speed parameter is more than 600 RPM. |
| • | The ignition is ON for more than 2 seconds. |
| • | The engine is running. |
| • | DTC P0068 runs continuously once the above conditions are met. |
Conditions for Setting the DTC
The PCM detects that the throttle position and indicated engine airflow do not correspond with the expected airflow and throttle position for longer than 300 milliseconds.
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. |
Step | Action | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views | |||||||||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |||||||
2 | Are DTCs P0101, P0102, P0103, P0107, P0108, P0120, P0220, P1106, P1107, U0107 also set? | Go to Step 3 | |||||||
3 |
Did the DTC fail this ignition? | Go to Step 4 | Go to Testing for Intermittent Conditions and Poor Connections | ||||||
4 | Inspect for the following conditions:
Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | ||||||
5 | Inspect the throttle body for the following conditions:
Did you find and correct the condition? | Go to Step 7 | Go to Step 6 | ||||||
6 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | Go to Step 7 | -- | ||||||
7 |
Did the DTC fail this ignition? | Go to Step 3 | Go to Step 8 | ||||||
8 |
Important: Be aware that repairing one individual condition may correct more than one DTC. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | System OK | |||||||
