Mitsubishi Electric Lancer Evolution-VII Workshop Manual page 952

When rotated with the hand
When idling (5 – 6 km/h)
1st gear
10.0 ms/DIV
IV/DIV
<Waveform observation points>
Phenomenon
Waveform amplitude is too small or
not output at all
Excessive waveform amplitude
(However allowed if above the (
minimum amplitude of 100 mV) i i lit d f 100
Noise in the waveform or waveform
is abnormal i b l
Caution
As the wheel speed sensor cable follows the movement of the front or rear suspension, it will
change considerably on poor condition roads. Therefore, also observe the output voltage waveform
of the wheel speed sensor with the sensor harness vibrated to simulate special conditions such
as driving in poor road conditions.
MANUAL TRANSMISSION - On-vehicle Service
4. If the output voltage is lower than the above values, the
INSPECTION PROCEDURE USING OSCILLOSCOPE
After checking the connected state of the harness of the
wheel speed sensor and connector, and measure the output
voltage waveform of each wheel speed sensor on the
oscilloscope as follows.
Start the engine, shift the transmission to the 1st gear to
rotate the driving wheel, and rotate the non-driving wheel
at constant velocity with the hand.
NOTE
1. It is also possible to actually drive the vehicle and observe
2. The output voltage is low if the wheel speed is low and
Probable cause
Wheel seed sensor fault
Excessive vibration or concentricity of
the axle hub
V)
4WD-ECU earth fault
Open circuit of the sensor
Open circuit of the harness
Wheel speed sensor installation fault
Chipping or flattening of the ABS rotor
Output voltage:
Above 70 mV when measured with the circuit
tester
Above 200 mVP-P when measured with the
oscilloscope
following reasons may be suspected. Check or replace
the wheel speed sensor.
Excessive clearance between the ball piece of the
D
wheel speed sensor and ABS rotor
Wheel speed sensor faul
D
the waveform.
gradually increases as the speed increases.
Solution
Replace the sensor
Replace the hub
Correct
Replace the sensor
Replace the harness
Correct the installation of the sensor
Replace the ABS rotor
22A-45