Oscilloscope Patterns and Waveforms

INSPECTING WAVE FORMS WITH AN OSCILLOSCOPE

Use the following method to observe the output voltage wave form from each wheel sensor with an oscilloscope
- Start the engine, and rotate the front wheels by engaging 1st gear (vehicles with manual transaxle) or D range (vehicles with automatic transaxle). Turn the rear wheels manually so that they rotate at a constant speed.

NOTE:
1. Check the connection of the sensor harness and connector before using the oscilloscope.
2. The wave form measurements can also be taken while the vehicle is actually moving.
3. The output voltage will be low when the wheel speed is low, and similarly it will be higher as the wheel speed increases.





POINTS IN WAVEFORM MEASUREMENT

NOTE: The wheel speed sensor cable moves following motion of the front or rear suspension. Therefore, it is likely that it has an open circuit only when driving on rough roads and it functions normally on ordinary roads. It is, therefore, recommended to observe sensor output voltage waveform also under special conditions, such as rough road driving.