Features such as superior magnetic circuit materials are engineered into Standard® sensors to deliver higher voltage output preventing ABS system failure. Standard® ABS speed sensors are designed to provide consistent performance, matching the OE for form, fit, and precision function. Standard® offers more than 2,500 ABS Speed Sensors for import and domestic applications for 96% coverage. When you need to replace an ABS sensor or just a connector or harness, look to Standard® for your next ABS repair. In addition to premium sensors Standard® offers complementary connectors and harnesses.
#PURPOSE OF ANTI LOCK BRAKING SYSTEM PROFESSIONAL#
Premium Replacements for an Important Safety CategoryĪlong with industry leading coverage, Standard® delivers the quality professional technicians depend on. This method is something any tech can perform. One method is to disconnect the sensor and module applying power at one end and a test light at the other end – this will load test the wiring. The wires must be load tested to check proper operation. The wires are low current and low voltage but must be in working condition. This test can be misleading and cause misdiagnosis. Many manufacturer trouble trees will have the technician do an open circuit check on the harness. The wires are subject to significant movement as the chassis and suspension moves, and there may be intermittent faults due to wiring defects. Regardless of sensor type, if a wheel speed sensor is suspected to be bad, it is important to also test the wiring to check proper operation. While this can be done with a meter, the most accurate method is to monitor it using a lab scope. If the resistance is in spec, the next test should be to measure the output. These are polarity sensitive so it is important that the meter is hooked up properly. If a technician needs to test an active wheel speed sensor, the simplest test is to ensure that the resistance is proper. There are only two possible state changes, and this creates an output of two different voltages.Īll active wheel speed sensors produce a digital signal, and typically the amplitude change is only about half of a volt. When a magnetic field is applied or increased within the sensor due to the rotating hub, the effective resistance of the sensor changes. The EBCM supplies the sensor with B+ through an internal resistor and ground, which creates a voltage divider circuit. As the reluctor passes by the wheel speed sensor, it will act as a variable resistor with two states. Instead of a hub with an embedded set of magnets, the hub has a simple reluctor. The type 2 active wheel speed sensor incorporates a magnet inside of the sensor itself. The EBCM supplies the sensor with B+ through an internal resistor and ground which creates a voltage divider circuit. As the hub moves past the sensor, the sensor’s resistance changes states. The type 1 sensor uses a hub that has magnets embedded into it with alternating polarity. While technically not accurate, for our purposes we will simplify the sensor’s operation by considering it essentially a variable resistor with two states high and low resistance. Within both types is a magneto-resistive circuit. There are two basic types we will arbitrarily refer to as type 1 and type 2. Responding to the need for better onboard diagnostics and the ability to detect even lower wheel speeds, engineers created the active wheel speed sensor. This test will prove that a sensor is bad if a high resistance is measured but does not prove the sensor is good. There could still be issues with the sensor, tone ring, and wiring. To test the resistance of a VRS, unplug the sensor and probe across the two wires. Air gap between the sensor and tone ring is critical.
#PURPOSE OF ANTI LOCK BRAKING SYSTEM MANUAL#
It is important to check the vehicle’s service manual to confirm these specs, though often the resistance spec will be found in a testing procedure instead of specs. Expected resistance will be somewhere between 1,000-2,500 ohms.
Technicians can test the resistance of the sensor with their Ohm meter. This is why VR sensors are not used in stability control systems. Signal strength is dependent upon speed and they are not effective at low speeds. VRS sensors do not require power to operate. The expanding and contracting magnetic field induces an AC voltage into the sensor, which is then recognized by the EBCM as a speed signal based on the frequency of the changes. As the cogs approach the sensor, the magnetic field expands and then when the cog moves away from the sensor, the magnetic field collapses. Signals are generated by rotating a metal reluctor past the sensor. These are VR or variable reluctance sensors and are essentially just a magnet within a coil of wire. The first and most widely used are called passive wheel speed sensors.
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