Circuit/System Description

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.

Circuit	Description
12V Reference	Regulated voltage supplied by the control module.
Signal	The control module input circuit has an internal resistance connected to 5 V.
Ground	Chassis Ground

Component	Description
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. Low temperature produces a high resistance: 1, 66 ohms @ 40°C (104°F) High temperature produces a low resistance: 97 ohms @ 130°C (266°F)
K20 Engine Control Module	The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensor s, interprets the data and adjusts the engine actuators accordingly.

Component

Description

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.
- Low temperature produces a high resistance: 1, 66 ohms @ 40°C (104°F)
- High temperature produces a low resistance: 97 ohms @ 130°C (266°F)

K20 Engine Control Module

The control module contains a microprocessor used to process input data to control outputs.
The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensor s, interprets the data and adjusts the engine actuators accordingly.