Circuit/System Description
| Component | Description |
|---|---|
| B74 Manifold Absolute Pressure Sensor | MAP Sensor |
| B75C Multifunction Intake Air Sensor | The assembly contains the following components:
|
| K20 Engine Control Module | The control module contains a microprocessor used to process input data to control outputs. |
B74 Manifold Absolute Pressure Sensor
The sensor is a capacitive pressure transducer. Electronics in the sensor convert pressure into an analog voltage signal.
B75C Multifunction Intake Air Sensor
The assembly has several functions:
The mass air flow sensor is a hot film type sensor that measures the mass of air (not the volume) entering the engine. The signal varies with engine load and is displayed by the scan tool in Hertz (Hz) and grams per second (g/s).
The intake air humidity sensor uses the same signal circuit as the intake air temperature sensor 2. The intake air humidity sensor modulates the pulse width of the signal. The intake air temperature sensor 2 modulates the frequency of the signal. That means the signal is both, PWM and FM modulated.
The barometric pressure sensor generates an analog voltage that is proportional to the ambient air pressure.
The intake air temperature sensor 1 varies its resistance depending on the temperature.
K20 Engine Control Module
This DTC sets when the control module detects an inconsistency between the pressure sensors and cannot identify which sensor failed.