Subaru 2009 IMPREZA Service Manual page 2509

Diagnostic Procedure with Diagnostic Trouble Code (DTC)
Step
1 WHETHER A WHEEL TURNED FREELY OR
NOT.
Check if the wheels have been turned freely for
one minute or more, such as when the vehicle is
jacked-up, under full-lock cornering or when the
wheels are not in contact with road surface.
2 CHECK TIRE SPECIFICATIONS.
Turn the ignition switch to OFF.
3 CHECK WEAR OF TIRE.
4 CHECK TIRE INFLATION PRESSURE.
5 CHECK INSTALLATION OF ABS WHEEL
SPEED SENSOR.
6 CHECK ABS WHEEL SPEED SENSOR SIG-
NAL.
1) Install the ABS wheel speed sensor.
2) Prepare an oscilloscope.
3) Check the ABS wheel speed sensor. <Ref.
to ABS-14, ABS WHEEL SPEED SENSOR,
INSPECTION, Front ABS Wheel Speed Sen-
sor.>
7 CHECK ABS WHEEL SPEED SENSOR OR
MAGNETIC ENCODER.
8 CHECK VDCCM&H/U.
1) Connect all connectors.
2) Clear the memory. <Ref. to VDC(diag)-24,
Clear Memory Mode.>
3) Perform the Inspection Mode. <Ref. to
VDC(diag)-23, Inspection Mode.>
4) Read the DTC.
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
Check
Did the wheels turn freely?
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
7.5 N·m (0.76 kgf-m, 5.5 ft-lb)?
(For four wheels)
Does the oscilloscope indicate
the waveform pattern like
shown in the figure when the
tire is slowly turned? Does the
oscilloscope indication repeat
the waveform pattern like
shown in the figure when the
tire is slowly turned in equal
speed for one rotation or more?
Are there foreign matter, break-
age or damage at the tip of ABS
wheel speed sensor or mag-
netic encoder?
Is the same DTC displayed?
VDC(diag)-47
Yes No
VDC is normal. Go to step 2.
Clear the memory.
NOTE:
This diagnostic
trouble code may
sometimes occur if
the wheels turn
freely for a long
time, for example
when the vehicle is
towed or jacked-
up, or when steer-
ing wheel is contin-
uously turned all
the way.
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.
Go to step 8. Go to step 7.
Remove dirt thor- Go to step 8.
oughly. Also
replace the ABS
wheel speed sen-
sor or magnetic
encoder as a unit
with hub unit bear-
ing if it is broken or
damaged.
Replace the Go to step 9.
VDCCM only.
<Ref. to VDC-9,
REPLACEMENT,
VDC Control Mod-
ule and Hydraulic
Control Unit
(VDCCM&H/U).>