Subaru Impreza 2003 Service Manual page 2457

DIAGNOSTICS PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
Step
11 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, the
ABSCM&H/U sometimes stores DTC 29 or
DTC 56.
Connector & terminal
DTC 22
LHD: (B15) No. 1 (+) — No. 2 ( − − − − ):
RHD: (F95) No. 1 (+) — No. 2 ( − − − − ):
DTC 24
LHD: (B62) No. 20 (+) — No. 24 ( − − − − ):
RHD: (F94) No. 1 (+) — No. 2 ( − − − − ):
DTC 26
LHD: (B99) No. 10 (+) — No. 9 ( − − − − ):
RHD: (B99) No. 32 (+) — No. 31 ( − − − − ):
DTC 28
LHD: (B99) No. 5 (+) — No. 4 ( − − − − ):
RHD: (B99) No. 21 (+) — No. 20 ( − − − − ):
12 CHECK CONTAMINATION OF ABS WHEEL
SPEED SENSOR OR TONE WHEEL.
Remove the disc rotor or drum from hub in
accordance with DTC.
13 CHECK DAMAGE OF ABS WHEEL SPEED
SENSOR OR TONE WHEEL.
14 CHECK TONE WHEEL RUNOUT.
Measure the tone wheel runout.
Check
Is an oscilloscope pattern
smooth, as shown in the fig-
ure?
Is the ABS wheel speed sen-
sor piece or tone wheel con-
taminated by dirt or other
foreign matter?
Are there broken or damaged
in the ABS wheel speed sen-
sor piece or tone wheel?
Is the runout less than 0.05
mm (0.0020 in)?
ABS-117
ABS (DIAGNOSTICS)
Yes
Go to step 15. Go to step 12.
Thoroughly Go to step 13.
remove dirt or
other foreign mat-
ter.
Go to step 14. Replace the ABS
wheel speed sen-
sor or tone wheel.
Front: <Ref. to
ABS-13, Front
ABS Wheel Speed
Sensor.> Rear:
<Ref. to ABS-16,
Rear ABS Wheel
Speed Sensor.>
and Front: <Ref. to
ABS-19, Front
Tone Wheel.>
Rear: <Ref. to
ABS-20, Rear
Tone Wheel.>
Go to step 15. Replace the tone
wheel. Front:
<Ref. to ABS-19,
Front Tone
Wheel.> Rear:
<Ref. to ABS-20,
Rear Tone
Wheel.>
No