Subaru 2002 IMPREZA Service Manual page 2153

DIAGNOSTICS CHART WITH DIAGNOSIS CONNECTOR
Step
1 CHECK IF THE WHEELS HAVE TURNED
FREELY FOR A LONG TIME.
2 CHECK TIRE SPECIFICATIONS.
Turn the ignition switch to OFF.
3 CHECK WEAR OF TIRE.
4 CHECK TIRE PRESSURE.
5 CHECK INSTALLATION OF ABS SENSOR.
Tightening torque:
32 N·m (3.3 kgf-m, 24 ft-lb)
6 CHECK ABS SENSOR GAP.
Measure the tone wheel to ABS sensor piece
gap over entire perimeter of the wheel.
Specifications
Front wheel
0.3 — 0.8 mm (0.012 — 0.031 in)
Rear wheel
0.7 — 1.2 mm (0.028 — 0.047 in)
7 PREPARE OSCILLOSCOPE.
8 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 AB-
SCM&H/U sometimes stores the DTC 29.
Connector & terminal
Front RH
LHD: (B15) No. 1 (+) — No. 2 ( − − − − ):
RHD: (F95) No. 1 (+) — No. 2 ( − − − − ):
Front LH
(F94) No. 1 (+) — No. 2 ( − − − − ):
Rear RH
LHD: (B99) No. 9 (+) — No. 10 ( − − − − ):
RHD: (B99) No. 20 (+) — No. 21 ( − − − − ):
Rear LH
LHD: (B99) No. 4 (+) — No. 5 ( − − − − ):
RHD: (B99) No. 8 (+) — No. 9 ( − − − − ):
Check
Check if the wheels have been
turned freely for more than 1
minute, such as when vehicle
is jacked-up, under full-lock
cornering or when tire is not in
contact with road surface.
Are the tire specifications cor-
rect?
Is the tire worn excessively?
Is the tire pressure correct?
Are the ABS sensor installation
bolts tightened securely?
Is the gap within the specifica-
tions?
Is an oscilloscope available?
Is the oscilloscope pattern
smooth, as shown in the fig-
ure?
ABS-55
ABS (DIAGNOSTICS)
Yes
The ABS is nor- Go to step 2.
mal. Erase the
DTC.
NOTE:
When the wheels
turn freely for a
long time, such as
when the vehicle is
towed or jacked-
up, or when steer-
ing wheel is contin-
uously turned all
the way, this DTC
may sometimes
occur.
Go to step 3. Replace the tire.
Replace tire. Go to step 4.
Go to step 5. Adjust tire pres-
sure.
Go to step 6. Tighten the ABS
sensor installation
bolts securely.
Go to step 7. 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 8. Go to step 9.
Go to step 12. Go to step 9.
No
tone