Subaru Impreza 2002 Service Manual page 2828

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR
Step
2 CHECK ABS SENSOR GAP.
Measure the tone wheel to ABS sensor piece
gap over entire perimeter of the wheel.
Front wheel
0.3 — 0.8 mm (0.012 — 0.031 in)
Rear wheel
0.7 — 1.2 mm (0.028 — 0.047 in)
3 PREPARE OSCILLOSCOPE.
4 CHECK ABS SENSOR SIGNAL.
1)Raise all four wheels off ground.
2)Turn the ignition switch to OFF.
3)Connect the oscilloscope to the connector.
4)Turn the ignition switch to ON.
5)Rotate the wheels and measure voltage at
specified frequency. <Ref. to ABS-17, WAVE-
FORM, Control Module I/O Signal.>
NOTE:
When this inspection is completed, the ABS
control module sometimes stores DTC 29.
Connector & terminal
DTC 22 /
LHD: (B15) No. 1 (+) — No. 2 ( − − − − ):
RHD: (F95) No. 1 (+) — No. 2 ( − − − − ):
DTC 24 /
LHD: (F45) No. 20 (+) — No. 24 ( − − − − ):
RHD: (F94) No. 1 (+) — No. 2 ( − − − − ):
DTC 26 /
LHD: (B99) No. 9 (+) — No. 10 ( − − − − ):
RHD: (B99) No. 20 (+) — No. 21 ( − − − − ):
DTC 28 /
LHD: (B99) No. 4 (+) — No. 5 ( − − − − ):
RHD: (B99) No. 8 (+) — No. 9 ( − − − − ):
5 CHECK CONTAMINATION OF ABS SENSOR
OR TONE WHEEL.
Remove the disc rotor or drum from hub in
accordance with DTC.
6 CHECK DAMAGE OF ABS SENSOR OR
TONE WHEEL.
Check
Is the gap within the specifica-
tions?
Is an oscilloscope available?
Is the oscilloscope pattern
smooth, as shown in figure?
Is the ABS sensor piece or the
tone wheel contaminated by
dirt or other foreign matter?
Are there broken or damaged
in the ABS sensor piece or the
tone wheel?
ABS-49
ABS (DIAGNOSTICS)
Yes
Go to step 3. Adjust the gap.
NOTE:
Adjust the gap us-
ing spacer (Part
No. 26755AA000).
If the spacer can-
not correct gap, re-
place worn sensor
or worn
wheel.
Go to step 4. Go to step 5.
Go to step 8. Go to step 7.
Thoroughly Go to step 6.
remove dirt or
other foreign mat-
ter.
Replace the ABS Go to step 7.
sensor or tone
wheel. Front:
<Ref. to ABS-14,
Front ABS Sen-
sor.> Rear: <Ref.
to ABS-17, Rear
ABS Sensor.> and
Front: <Ref. to
ABS-20, Front
Tone Wheel.>
Rear: <Ref. to
ABS-21, Rear
Tone Wheel.>
No
tone