Theory Of Operation
| COMPONENT | LOCATION | CORRELATING PRESSURE SENSOR DTCS | CORRELATING TEMP SENSOR DTCS |
|---|---|---|---|
| BARO SENSOR | Inside the PCM | P0109, P2227, P2228, P2229, P3032 | N/A |
| Mass Air Flow (MAF) Sensor | Before the Throttle Body | P0102, P0103, P1613 | P0111, P0112, P0113 |
| Supercharger Inlet MAP Sensor | Between the Throttle Body and Supercharger | P0069, P012A, P012B, P012C, P012D, P1613 | P0096, P0097, P0098 |
| Supercharger Outlet MAP Sensor | On the Intake Manifold directly after the Supercharger | P00F8, P00F9, P00FA, P00FB, P0607 | P00E9, P00EA, P00EB |
| Bank 1 MAP Sensor | Right side of the Intake Manifold | P0105, P0106, P0107, P0108, P0607 | P07B, P007C, P007D |
| Bank 2 MAP Sensor | Left side of the Intake Manifold | P2A0A, P2A0B, P2A0C, P2A0D, P0607 | P00A1, P00A2, P00A3 |
The MAF Sensor and each of the four MAP Sensors also have an integral air temperature sensor. The temperature sensors have a 5.0 volt signal circuit and share the sensor ground circuit with the pressure sensor. They do not share the 5-Volt Reference circuit with the pressure sensor and therefore operate as a typical two wire temperature sensor.
The 6.2L engine uses several sensors to monitor the air pressure and temperature throughout the intake air system. The PCM uses this information to help calculate fuel delivery, ignition timing and Supercharger control. The PCM runs diagnostics to check the rationality of the sensors. The Supercharger Inlet Pressure Sensor is the centralized sensor in the system and is the main sensor used for the rationality diagnostics of the airflow before and after the Throttle Body.
Individual MAP/Pressure Sensor rationality diagnostic checks:
- At ignition on, engine not running, the BARO Sensor and four MAP/Pressure Sensor input signals are compared. If one of the MAP/Pressure Sensor input signals has a difference of more than a calibrated threshold from the others, a performance fault is set against that sensor.
- With the engine running, the input signals of the three MAP/Pressure Sensors that are downstream of the Supercharger Inlet Pressure Sensor (Supercharger Outlet Pressure Sensor, Bank 1 MAP, Bank 2 MAP) are compared. If one of the sensor input signals has more than a 10.0 kPa (1.5 psi) difference from the other two, a performance fault is set against that sensor.
BARO/Supercharger Inlet Pressure Sensor rationality diagnostic check:
- The Supercharger Inlet Pressure Sensor signal is compared to the BARO signal to check rationality of the sensors. During natural aspiration, the Supercharger Inlet Pressure Sensor signal cannot be greater than the BARO signal plus 10.3 kPa (1.49 psi). During boost conditions, the Supercharger Inlet Pressure Sensor signal and BARO signal pressures should be similar. If the diagnostic fails during a drive cycle, a fault is set (P0069) and the secondary Supercharger Inlet Pressure Sensor rationality diagnostic is run to determine which sensor is irrational.
MAF/Supercharger Inlet Pressure Sensor rationality diagnostic check:
- This diagnostic runs continuously, unless any airflow, throttle, MAF, BARO, or Supercharger Inlet Pressure Sensor diagnostics have failed. Then using the pressure differential across the throttle opening (BARO - Supercharger Inlet Pressure Sensor), the PCM models the mass air flow volume through the Throttle Body. This modeled value is compared to the actual MAF Sensor signal input to the PCM. If the difference is greater than a calibrated threshold, a fault is set (P1613) and the secondary Supercharger Inlet Pressure Sensor rationality diagnostic is run to determine which sensor is irrational.
Supercharger Inlet Pressure Sensor rationality diagnostic check:
- If either of the first two diagnostics fail during a given trip, or if one of the downstream MAP/Pressure Sensors is determined to be irrational, the PCM runs a secondary diagnostic to determine if the Supercharger Inlet Pressure Sensor is rational. With the engine in a natural aspiration condition (not boosted), the PCM compares the signal input from the Supercharger Inlet Pressure Sensor to the signal inputs from the Supercharger Outlet Pressure Sensor, Bank 1 MAP, and Bank 2 MAP Sensors. If the Supercharger Inlet Pressure Sensor is not within a calibrated threshold of the other three MAP/Pressure Sensors, it is determined to be irrational and a fault is set (P121B).
Temperature sensor rationality checks:
- After a cold soak of the engine, the Engine Coolant Temperature (ECT) and Ambient Air Temperature (AAT) Sensor inputs are compared to the inputs form each of the temperature sensors located in the MAF and MAP Sensors. If a temperature sensor is not within a calibrated threshold of the ECT or AAT Sensors, a performance fault is set.