The computers on modern vehicles receive and process information from many different sensors. When these sensors fail or function incorrectly, it can lead to drivability and safety issues. Our common automotive sensor guide can help you understand the complex components that make up a modern automobile.
ABS Speed Sensor
Monitors wheel speed and communicates with the ABS computer, which uses the information to prevent brakes from locking during an emergency stop.
Accelerator Pedal Position Sensor
Indicates accelerator position on vehicle models with electronic throttle control.
Ambient Air Temp Sensor
Changes resistance with temperature, which the computer uses to trim air/fuel ratio according to air density.
Camshaft Position Sensor
Determines which cylinder is firing to establish injector synchronization and coil firing sequence in DIS systems.
Coolant Temperature Sensor
Changes resistance with temperature, which the computer uses to trim fuel delivery and timing based on engine coolant temperature.
Crankshaft Position Sensor
Provides computer with crankshaft position and RPM information for calculating injector repetition, timing advance, and distributorless ignition synchronization.
EGR Valve Position Sensor
Detects movement and position of the EGR valve pintle and sends it to the computer, which uses the information to control EGR flow to engine and trim air/fuel ratio.
Knock (Detonation) Sensor
Manifold Absolute Pressure Sensor
Converts engine vacuum/manifold pressure to electrical signal, which the computer uses to determine how much load the engine is under. This data is the basis for fuel delivery and timing control.
Mass Air Flow (MAF) Sensor
Measures the amount of airflow entering intake manifold and communicates with the Engine Control Module (ECM) for fuel and timing control.
Throttle Position Sensor
Moves with the throttle and creates voltage signal indicating throttle angle and speed of movement data, which the computer uses to measure engine load, clear flood mode, and adjust timing, fuel delivery, EGR, and converter clutch operation.
Tire Pressure Monitoring (TPMS) Sensors
Measures, identifies, and warns the driver when one or more tires is significantly under-inflated. Each sensor transmits temperature, air pressure, battery state, and sensor location to the vehicle’s computer.
Vehicle Speed Sensor
Measures transmission/transaxle output or wheel speed, which the ECM uses to modify engine functions such as ignition timing, AF ratio, transmission shift points, and initiating diagnostic routines.
Check out all the relays, sensors and switches
Photo courtesy of Wikimedia Commons.
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