Subaru Impreza 2003 Service Manual page 2456

DIAGNOSTICS PROCEDURE WITH DIAGNOSTIC TROUBLE CODE (DTC)
ABS (DIAGNOSTICS)
Step
1 CHECK OUTPUT OF ABS WHEEL SPEED
SENSOR USING SUBARU SELECT MONI-
TOR.
1)Select "Current data display & Save" on the
Subaru Select Monitor.
2)Read the ABS wheel speed sensor output
corresponding to faulty system in the Subaru
Select Monitor data display mode.
2 CHECK POOR CONTACT IN CONNECTORS.
Turn the ignition switch to OFF.
3 CHECK SOURCES OF SIGNAL NOISE.
4 CHECK SOURCES OF SIGNAL NOISE.
5 CHECK SHIELD CIRCUIT.
1)Turn the ignition switch to OFF.
2)Connect all connectors.
3)Measure the resistance between shield con-
nector and chassis ground.
Connector & terminal
DTC 22
LHD: (B303) No. 2 — Chassis ground:
RHD: (F62) No. 2 — Chassis ground:
DTC 24
LHD: (B303) No. 1 — Chassis ground:
RHD: (F62) No. 1 — Chassis ground:
NOTE:
If the DTC is 26, 28: Go to YES.
6 CHECK ABSCM&H/U.
1)Connect all connectors.
2)Erase the memory.
3)Perform the inspection mode.
4)Read out the DTC.
7 CHECK ANY OTHER DTC APPEARANCE.
8 CHECK INSTALLATION OF ABS WHEEL
SPEED SENSOR.
9 CHECK ABS WHEEL SPEED SENSOR GAP.
Measure the tone wheel to ABS wheel speed
sensor piece gap over entire perimeter of
wheel.
10 PREPARE OSCILLOSCOPE.
Check
Does the speed indicated on
display change in response to
speedometer reading during
acceleration/deceleration
when the steering wheel is in
straight-ahead position?
Is there poor contact in con-
nectors between ABSCM&H/U
and ABS wheel speed sensor?
Is the car telephone or wireless
transmitter properly installed?
Are noise sources (such as an
antenna) installed near the
sensor harness?
Is the resistance less than 0.5
Ω?
Is the same DTC as in the cur-
rent diagnosis still being out-
put?
Are other DTCs being output? Proceed with the
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?
ABS-116
Yes
Go to step 2. Go to step 8.
Repair the con- Go to step 3.
nector.
Go to step 4. Properly install the
car telephone or
wireless transmit-
ter.
Install the noise Go to step 5.
sources apart from
sensor harness.
Go to step 6. Repair the shield
harness.
Replace the Go to step 7.
ABSCM&H/U.
<Ref. to ABS-7,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>
A temporary noise
diagnosis corre- interference.
sponding to DTC.
Go to step 9. Tighten the ABS
wheel speed sen-
sor installation
bolts securely.
Go to step 10. 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 11. Go to step 12.
No
tone