Sensors for trucks

Sensors are used in virtually all electronic systems of modern trucks. The main purpose of the components is monitoring the safety of driving and informing the driver about the state of the components. Due to the presence of indicators, a truck owner can determine when service is required.

Kinds of sensors for trucks

By the operating principle:

• Active. They operate due to receiving external signals. Reacting to these signals, devices convert their own internal characteristics into electrical signals.
• Passive. They do not need additional signal sources. They can produce and send electrical signals.

Depending on the scope of use, the following types are distinguished:

• Position and speed sensors. These include detectors of the position of crankshaft, camshaft, throttle and accelerator pedal, as well as devices for monitoring fuel level, the wheel speed, and the steering angle. The devices can be with and without contacts. Operation of the latter is based on physical phenomena and effects. These include Hall sensors, Wiegand sensors, inductive, magnetoresistive, optical, and other sensors. These devices are potentiometers with moving contacts that measure angular and linear movements of objects.
• Air flow sensors. Such devices are located in front of the air filter. They are used for determining the amount of air entering the engine.
• Monitoring exhaust gases. This category includes lambda sensors and detectors of the nitric oxide level, which are installed in the exhaust system. They inform about the amount of harmful substances in the exhaust gases.
• Temperature sensors. These are thermo-resistors with a negative temperature coefficient. They are installed in the intake manifold, in and outside the cab of the truck. They also allow determining coolant and oil temperature.
• Pressure sensors. These are used in lubrication, fuel injection, and brake systems. In addition, they are used for determining the pressure in the intake manifold and in tires.

Malfunctions and reasons thereto

Like sensors of passenger cars, devices used in trucks get out of order in case of mechanical damage and oxidation of contacts, breakage and abrasion of the resistive layer. The reason is often incorrect repair in the engine compartment, wire insulation failure, improper installation, and ingress of moisture and abrasive particles.

How to detect faults

The components do not have a specified service life. The need for diagnostics is indicated by corresponding indicators on the dashboard.

Indirect symptoms are malfunctions of relevant units. For example, failures of some detectors of position and speed may indicate loss of power, or inability to start the engine, increased fuel consumption, jerks when the accelerator pedal is pressed. In addition, disruptions in the operation of speedometer, odometer and gearbox are likely.

If detectors of air flow and harmful substances in the exhaust gases are faulty, loss of engine power, unstable idling is observed; extraneous sounds from the muffler are heard. Failure of temperature sensors is indicated by engine overheating.

Components have to be diagnosed at a service station with the use of special equipment: a multimeter, a pressure gauge, etc. Replacement of damaged components should also do professionals.

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