ABS Wheel Speed Sensors

On the vehicle you have been assigned does it use analogue or digital wheel sensors?

Analogue

How did you conclude the wheel sensors were analogue or digital?

Because there are only 2 wires on the sensors. Digital sensors have three.

Measure the air gap for each sensor. State the air gap and visual condition of each wheel sensor.

Front Right

.838. The air gap was good, the gap should be between .4 and 1mm

Front Left

.838. The air gap is good. The gap is between the specifications, and there is no visual wear to the sensor.

Rear Right

1.043. The air gap is off and needs to be adjusted. No evidence of wear

Rear Left

1.043. The air gap is off and needs to be adjusted. No evidence of wear.

Using an oscilloscope connect it to a wheel sensor and record the pattern shown, If the sensor is a analogue sensor then just connect the probe and spin the wheel. If the sensor is digital you will need to have the ignition before you turn the wheels. (Left Image Front Wheel Sensor), (Right Image Rear Wheel Sensor)

Is this pattern analogue or digital?

Analogue

Using the frequency scale on a multimeter. Turn the wheel approximately the same speed as in the above test. Note the frequency and compare it to the graph you drew above.

Frequency Observations....

My recorded results when measuring the frequency of the wheels with a multimeter were 2.96 and 2.97 KHz for the front wheel sensors and 3.15-3.16 KHz for the rear wheel sensors. Meaning the rear wheels were spinning slighty faster.