Subaru Impreza 2003 Service Manual page 2463

DIAGNOSTICS PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
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 WHEEL
SPEED SENSOR.
6 CHECK ABS WHEEL SPEED SENSOR GAP.
Measure the tone wheel to ABS wheel speed
sensor piece gap over entire perimeter of the
wheel.
7 PREPARE OSCILLOSCOPE.
8 CHECK ABS WHEEL SPEED SENSOR SIG-
NAL.
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-16, WAVE-
FORM, Control Module I/O Signal.>
NOTE:
When this inspection is completed, ABSCM&
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
LHD: (B62) No. 20 (+) — No. 24 ( − − − − ):
RHD: (F94) No. 1 (+) — No. 2 ( − − − − ):
Rear RH
LHD: (B99) No. 10 (+) — No. 9 ( − − − − ):
RHD: (B99) No. 32 (+) — No. 31 ( − − − − ):
Rear LH
LHD: (B99) No. 5 (+) — No. 4 ( − − − − ):
RHD: (B99) No. 21 (+) — No. 22 ( − − − − ):
Check
Is the wheels have been
turned freely for more than one
minute, such as when vehicle
is jacked-up, under full-lock
cornering or the tires 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 wheel speed sen-
sor installation bolts tightened
33 N·m (3.3 kgf-m, 24 ft-lb)?
Is the gap as following value?
Front wheel:
0.3 — 0.8 mm (0.012 — 0.031
in)
Rear wheel:
0.7 — 1.2 mm (0.028 — 0.047
in)
Is an oscilloscope available?
Is an oscilloscope pattern
smooth, as shown in the fig-
ure?
ABS-123
ABS (DIAGNOSTICS)
Yes
Go to step 2. The ABS is nor-
mal. Erase the
DTC.
NOTE:
When the wheels
turn freely for a
long time, such as
when
towed or jacked-
up, or when steer-
ing wheel is contin-
uously turned all
way, this DTC may
sometimes occur.
Go to step 3. Replace the tire.
Replace the tire. Go to step 4.
Go to step 5. Adjust the tire
pressure.
Go to step 6. Tighten the ABS
wheel speed sen-
sor installation
bolts securely.
Go to step 7. Adjust the gap.
NOTE:
Adjust the gap us-
ing spacer (Part
No. 26755AA000).
If the spacers 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
vehicle is
tone