B. WHEEL SPEED SENSOR Working principle: It is an active wheel speed sensor, which means that it must be connected to a voltage source for operation. It supplies a signal with constant amplitude pulses whose frequency varies with the wheel speed. It uses Hall Effect principle, it has a semiconductor chip with the electronic circuitry for supply and signal processing integrated on it. This chip is located within a completely insulated magnetic circuit consisting of permanent magnet and pole elements. The wheel speed sensor is mounted directly above the magnetized toner wheel. The magnetized toner wheel is a ring with teeth on it. The toner wheel is fitted on to the wheel hub. The alternating teeth and gap that accompanies the wheel rotation induces differential magnetic flux density, thus leading to the variation in the voltage induced in the semiconductor chip. The signal conditioning circuit converts this voltage variation into constant amplitude current pulses. The frequency of these pulses depends up on the wheel speed. This measurement principle permits zero speed measurement. Precise alignment and gap (1 mm) between the stator pole and the Toner wheel is vital. To obtain correct signal, the specified gap between the end of sensor & the toner ring must be maintained. Front : 0.5 mm to 1.5 mm Rear : 0.1 mm to 1.4mm Precautions while handling wheel speed sensor 1. Storage temperature (- 40°C to + 115°C) should not be exceeded. 2. Avoid free fall of the sensor. 3. The sensor tip should not be scratched. 4. Sensor should not be exposed to strong magnetic field. C. ABS SYSTEM FAILURE WARNING LIGHT CAUSE OF SYSTEM FAILURE SYSTEM WARNING LAMP ABS EBD ABS EBD None Operate Operate OFF OFF 1. Sensor failure Does not Operate Operate ON OFF 2. Pump failure Does not Operate Operate ON ON 3. Low voltage of battery Does not Operate Operate (at = 6.5V) ON V>8.4 OFF V<8.4 ON 4. Failure of 2 or more sensors Valve failure ECU failure Other failure Does not Operate Does not Operate ON ON BRAKE (MR) 21
RkJQdWJsaXNoZXIy MTIwNTUz