• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
• | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
• | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
The actual throttle position and airflow rate is compared to an expected throttle position and airflow rate based on engine load. The engine control module (ECM) 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.
The ECM uses the following information to calculate an expected airflow rate:
• | The throttle position (TP) |
• | The barometric pressure (BARO) |
• | The manifold absolute pressure (MAP) |
• | The supercharger inlet absolute pressure (SCIAP) |
• | The intake air temperature (IAT) |
• | The engine RPM |
• | DTCs P0122, P0123, P0220, P0221, P0222, P0223, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, P1516, P2101, P2119, P2135, P2176, P2610 are not set. |
• | The engine is running. |
• | DTC P0068 runs continuously when the above conditions are met. |
• | DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0116, P0128, P0122, P0123, P0220, P0221, P0222, P0223, P0335, P0336, P0401, P0405, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, P1404, P1516, P2101, P2119, P2135, P2176, P2610 are not set. |
• | The engine coolant temperature (ECT) is between 70-121°C (158-249°F). |
• | The engine IAT is between -7 and +60°C (+19 and +140°F). |
• | The engine is running. |
• | DTC P0121 runs continuously when the above conditions are met. |
The ECM detects that the airflow rate is greater than the calculated airflow for greater than 0.2 second.
• | DTC P0068 is a Type A DTC. |
• | DTC P0121 is a Type B DTC. |
• | DTC P0068 is a Type A DTC. |
• | DTC P0121 is a Type B DTC. |
Throttle Actuator Control (TAC) System Description
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle . |
⇒ | If the MAP sensor parameter does not decrease, refer to DTC P0106 . |
⇒ | If the SC Inlet Pressure Sensor parameter does not decrease, refer to DTC P0128 . |
Important: You must perform the Circuit/System Verification before proceeding with the Circuit/System Testing.
• | Vacuum hoses for splits, leaks, and improper connections |
• | Air leaks at throttle body mounting area and intake manifold sealing surfaces |
• | A supercharger bypass valve that is binding or incorrectly adjusted--Refer to Supercharger Cleaning and Inspection . |
• | Inspect throttle body for dirt, debris, and coking. Refer to Throttle Body Inspection and Cleaning . |
⇒ | If any of the above conditions are found, repair as necessary. |
⇒ | If greater than 4 volts or less than 0.8 volt, refer to DTC P0106 . |
⇒ | If the MAP sensor kPa does not change, refer to DTC P0106 . |
4.1. | Idle the engine. |
4.2. | Increase the engine speed slowly to 3,000 RPM, then back to idle. |
4.3. | Exit from the snapshot and review the data. |
4.4. | Observe the Mass Air Flow (MAF) Sensor parameter frame by frame with a scan tool. The MAF sensor g/s should change smoothly and gradually as the engine speed is increased and is returned to idle. |
⇒ | If the MAF sensor g/s does not change smoothly and gradually as the engine speed is increased and is returned to idle, refer to DTC P0101 or P1101 . |
⇒ | If TP Sensor 1 and TP Sensor 2 parameters differ more than 4 percent, refer to DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 . |
Caution: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.
• | Loose or damaged throttle blade |
• | Broken throttle shaft |
• | Any throttle body damage |
⇒ | If any of these conditions exist, replace the throttle body assembly. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup, and programming |