ABS (DIAGNOSTICS) > Diagnostic Procedure with Diagnostic Trouble Code (DTC) > DTC C0108 FRONT ABS WHEEL SPEED SENSOR LH MALFUNCTION (ABS WHEEL SPEED SENSOR ABNORMAL SIGNAL)

DTC C0108 FRONT ABS WHEEL SPEED SENSOR LH MALFUNCTION (ABS WHEEL SPEED SENSOR ABNORMAL SIGNAL)

DTC DETECTING CONDITION:

• Defective ABS wheel speed sensor signal (noise, abnormal signal, etc.)

• Defective harness connector

TROUBLE SYMPTOM:

ABS does not operate.

WIRING DIAGRAM:

• LHD model

• RHD model

STEP	CHECK	YES	NO
1.CHECK OUTPUT OF ABS WHEEL SPEED SENSOR USING SUBARU SELECT MONITOR. 1) Select {Current Data Display & Save} in Subaru Select Monitor. 2) Read the defective ABS wheel speed sensor output.	Does the speed indicated on the display change in response to the speedometer reading during acceleration/deceleration when the steering wheel is in the straight-ahead position?
2.CHECK POOR CONTACT IN CONNECTOR. Turn the ignition switch to OFF.	Is there poor contact in connectors between ABSCM&H/U and ABS wheel speed sensor?	Repair the connector.
3.CHECK CAUSE OF SIGNAL NOISE. Make sure the radio wave devices and electric components are installed correctly.	Are radio wave devices such as car phone or radio, and electronic components installed correctly?		Install the radio wave devices and electric components properly.
4.CHECK CAUSE OF SIGNAL NOISE. Check if the noise sources (such as an antenna) are installed near the sensor harness.	Are noise sources installed?	Install the noise sources apart from sensor harness.
5.CHECK ABSCM&H/U. 1) Connect all the connectors. 2) Clear the memory. 3) Perform the Inspection Mode. 4) Read the DTC.	Is the same DTC displayed?	Replace the ABSCM only.
6.CHECK FOR ANY OTHER DTC ON DISPLAY.	Is there any other DTC displayed?	Perform the diagnosis according to DTC.	It results from a temporary noise interference.
7.CHECK INSTALLATION OF ABS WHEEL SPEED SENSOR.	Is the ABS wheel speed sensor installation bolt tightened 7.5 N·m (0.76 kgf-m, 5.5 ft-lb)?		Tighten the ABS wheel speed sensor installation bolts.
8.CHECK ABS WHEEL SPEED SENSOR SIGNAL. 1) Install the ABS wheel speed sensor. 2) Prepare an oscilloscope. 3) Check the ABS wheel speed sensor.	Does the oscilloscope indicate the waveform pattern like shown in the figure when the tire is slowly turned? Does the oscilloscope indication repeat the waveform pattern like shown in the figure when the tire is slowly turned at equal speed for one rotation or more?
9.CHECK ABS WHEEL SPEED SENSOR OR MAGNETIC ENCODER.	Are there foreign matter, breakage or damage at the tip of ABS wheel speed sensor or magnetic encoder?	Remove dirt thoroughly. Also replace the ABS wheel speed sensor or magnetic encoder as a unit with hub unit bearing if it is broken or damaged.
10.CHECK CAUSE OF SIGNAL NOISE. Make sure the radio wave devices and electric components are installed correctly.	Are radio wave devices such as car phone or radio, and electronic components installed correctly?		Install the radio wave devices and electric components properly.
11.CHECK CAUSE OF SIGNAL NOISE. Check if the noise sources (such as an antenna) are installed near the sensor harness.	Is the noise sources installed?		Install the noise sources apart from sensor harness.
12.CHECK ABSCM&H/U. 1) Connect all the connectors. 2) Clear the memory. 3) Perform the Inspection Mode. 4) Read the DTC.	Is the same DTC displayed?	Replace the ABSCM only.
13.CHECK FOR ANY OTHER DTC ON DISPLAY.	Is any other DTC displayed?	Perform the diagnosis according to DTC.	It results from a temporary noise interference. NOTE: Though the ABS warning light remains on at this time, it is normal. Drive the vehicle at 12 km/h (7 MPH) or more in order to turn ABS warning light off. Be sure to drive the vehicle and check that the warning light goes off.