Subaru Impreza 2003 Service Manual page 2403

DIAGNOSTICS PROCEDURE WITHOUT DIAGNOSTIC TROUBLE CODE (DTC)
Step
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, 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
LHD: (F45) 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. 20 (+) — No. 21 ( − − − − ):
9 CHECK CONTAMINATION OF ABS WHEEL
SPEED SENSOR OR TONE WHEEL.
Remove the disc rotor or drum from hub.
10 CHECK DAMAGE OF ABS WHEEL SPEED
SENSOR OR TONE WHEEL.
11 CHECK TONE WHEEL RUNOUT.
Measure the tone wheel runout.
12 CHECK ABSCM&H/U.
1)Turn the ignition switch to OFF.
2)Connect all connectors.
3)Erase the memory.
4)Perform the inspection mode.
5)Read out the DTC.
Check
Is an oscilloscope pattern
smooth, as shown in the fig-
ure?
Is the ABS wheel speed sen-
sor piece or the tone wheel
contaminated by dirt or other
foreign matter?
Are there broken or damaged
teeth in the ABS wheel speed
sensor piece or the tone
wheel?
Is the runout less than 0.05
mm (0.0020 in)?
Is the same DTC as in current
diagnosis still being output?
ABS-63
ABS (DIAGNOSTICS)
Yes
Go to step 12. Go to step 9.
Thoroughly Go to step 10.
remove dirt or
other foreign mat-
ter.
Replace the ABS Go to step 11.
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 12. Replace the tone
wheel. Front:
<Ref. to ABS-19,
Front Tone
Wheel.> Rear:
<Ref. to ABS-20,
Rear Tone
Wheel.>
Replace the Go to step 13.
ABSCM&H/U.
<Ref. to ABS-7,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>
No