Subaru Impreza 2003, Service Manual

Page: 2395 / 3610

ABS-55
ABS (DIAGNOSTICS)
DIAGNOSTICS PROCEDURE WITHOUT DIAGNOSTIC TROUBLE CODE (DTC)
2 CHECK ABS WHEEL SPEED SENSOR GAP.
Measure the tone wheel to ABS wheel speed
sensor piece gap over entire perimeter of the
wheel.
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) 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 tone
wheel.
3 PREPARE OSCILLOSCOPE. Is an oscilloscope available? Go to step 4. Go to step 5.
4 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 ABS
control module 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: (F45) 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. 20 (+) — No. 21 (
−−−−
):
Is an oscilloscope pattern
smooth, as shown in the fig-
ure? Go to step 8. Go to step 7.
5 CHECK CONTAMINATION OF ABS WHEEL
SPEED SENSOR OR TONE WHEEL.
Remove the disc rotor or drum from hub in
accordance with DTC.
Is the ABS wheel speed sen-
sor piece or the tone wheel
contaminated by dirt or other
foreign matter? Thoroughly
remove dirt or
other foreign mat-
ter. Go to step 6.
6 CHECK DAMAGE OF ABS WHEEL SPEED
SENSOR OR TONE WHEEL. Are there broken or damaged
in the ABS wheel speed sen-
sor piece or the tone wheel? 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 7.
Step Check Yes No