* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download TECHNICAL TRAINING TIP 017 Method for the diagnosis of ABS
Survey
Document related concepts
Neutron magnetic moment wikipedia , lookup
Lorentz force wikipedia , lookup
Magneto (comics) wikipedia , lookup
Electrical resistance and conductance wikipedia , lookup
Magnetic monopole wikipedia , lookup
Earth's magnetic field wikipedia , lookup
Magnetotactic bacteria wikipedia , lookup
Electromagnetic field wikipedia , lookup
Magnetometer wikipedia , lookup
Superconducting magnet wikipedia , lookup
Electromagnet wikipedia , lookup
Giant magnetoresistance wikipedia , lookup
Multiferroics wikipedia , lookup
Magnetochemistry wikipedia , lookup
Magnetoreception wikipedia , lookup
History of geomagnetism wikipedia , lookup
Magnetohydrodynamics wikipedia , lookup
Transcript
TECHNICAL TRAINING TIP 017 Method for the diagnosis of ABS sensors With the advent of the magneto resistive sensors toward the end of the 1990s, diagnosis of ABS sensors has become more complex. Magneto resistive sensors are characterized by the fact that they can detect very low magnetic fields. Their principle of operation is based on the variation of the electric resistance of a ferromagnetic material as function of the applied magnetic field. When subjected to a magnetic field, the resistance decreases by 10% to 15%, which in turn decreases current flow by 7 to 14 milliamps. Unlike the pulse generator sensor, the voltage variation of a magneto resistive sensor is minimal; it is the variation of its current which acts on the PCM’s Schmitt trigger. Magneto resistive Sensor It is difficult to diagnose this type of sensor using an oscilloscope since the change in the sensor’s voltage, depending on the application, is only a few hundred millivolts. The magneto resistive sensor is also sensitive to variations in external magnetic fields, which implies that the object to detect must not have varying magnetic fields. Any accumulation of corrosion on the surface of the reluctor will also adversely affect the signal. The most common symptom is the activation of the isolation valve during low speed braking with no ABS intervention. The most effective method to detect the faulty wheel is by monitoring, with a scanner in graphical mode, the isolation valves. The valve which is activated during braking will identify the wheel with the faulty sensor. © OBD3 Solutions 2009 -1- Diagnosis using a scanner in graphical mode The above graph shows the activation of the isolation valve of the RH rear wheel. The above graph shows a cut in the rear RH ABS sensor. Caution: Before replacing the sensor, check that the reluctor is not damaged and is free of any corrosion. Also check the condition of wheel bearings. © OBD3 Solutions 2009 -2-