Circuit Description
The throttle position (TP) is compared to an expected throttle position based on engine load. The engine control module (ECM) determines engine load based on inputs from the mass air flow (MAF) and the manifold absolute pressure (MAP) sensors. If the ECM detects that the current load and throttle position are not consistent with the expected load and throttle position, DTC P0068 is set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0068 Throttle Body Airflow Performance
Conditions for Running the DTC
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0120, P0121, P0122, P0123, P0220, P0221, P0222, P0223, P0601, P0602, P0603, P0604, P0606, P0607, P1516, P2101 are not set. |
| • | The engine speed is more than 600 RPM and less than 6,300 RPM. |
| • | DTC P0068 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
The ECM detects that the throttle position and the indicated engine load do not correspond with the expected load and throttle position for less than one 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. |
Step | Action | Value(s) | Yes | No | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine 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, P0106, P0107, P0108, P0120, P0121, P0122, P0123, P0220, P0222, P0223, P1516, P2101, P2119, P2176 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 12 | Go to Step 5 | ||||||||
5 |
Important: Observe the throttle position (TP) sensors 1 and 2 angle parameter with a scan tool.
Is the difference between the TP sensor 1 angle and the TP sensor 2 angle less than the specified value? | 3% | Go to Step 10 | Go to Step 6 | ||||||||
6 | Test the TP sensor 1 5-volt reference circuit for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 7 | ||||||||
7 | Test the TP sensor low reference circuit for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 8 | ||||||||
8 | Test the TP sensor 1 signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 9 | ||||||||
9 | Test the TP sensor 2 signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 12 | Go to Step 10 | ||||||||
10 | Inspect the throttle body for the following conditions:
Did you find a condition? | -- | Go to Step 11 | -- | ||||||||
11 | Replace the throttle body assembly. Refer to Throttle Body Assembly Replacement . Did you complete the replacement? | -- | Go to Step 12 | -- | ||||||||
12 |
Did the DTC fail this ignition? | -- | Go to Step 3 | Go to Step 13 | ||||||||
13 |
Important: More than one throttle actuator control (TAC) system-related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual condition may correct more than one DTC. Be aware of this when reviewing Captured Info. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||||
