REAR AXLE – On-vehicle Service <Vehicles with AYC>
27-32
Waveform Observation Points
Symptom Probable cause Action
Waveform amplitude is too small, or no
waveform.
Defective speed sensor Replace sensor.
Waveform amplitude varies greatly. (No
f
the smallest amplitude is100
Excessive axle hub lateral and radial runout Replace hub.
mV or more)
Poor AYC-ECU grounding Repair.
Noise on waveform or disturbed
f
Open-circuited sensor Replace sensor.
wave
orm
Open-circuited harness Repair harness.
Improperly mounted speed sensor Correct sensor installation.
Missing or collapsed rotor tooth Replace rotor.
Caution
Since the speed sensor cable follows the movement of the front or rear suspension, it may be
open-circuited only when the vehicle is run on rough roads and not on ordinary road. The speed
sensor output voltage waveform should therefore be checked also by rocking the sensor harness
so that driving on rough roads may be simulated.
8. ACTION WHEN BATTERY RUNS OUT
When the engine is started using a booster cable where the
battery has completely run down and you attempt to start
the vehicle without waiting for the battery to recover a certain
charge, the engine can misfire and you just cannot start to
move it. In such cases, charge the battery sufficiently; or,
remove the AYC fusible link from the engine compartment
relay box to make AYC inactive before attempting to start
the vehicle. When the fusible link is removed, the AYC warning
lamp lights up. After the battery has been recharged, fit the
fusible link back again and start the engine to ensure that
the AYC warning lamp is off.
AYC fusible link
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