Subaru Legacy IV (2008 year). Service manual — part 946
VDC(diag)-99
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
AZ:DTC C0074 PRESSURE SENSOR
DTC DETECTING CONDITION:
Defective pressure sensor
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
Step
Check
Yes
No
1
CHECK STOP LIGHT SWITCH CIRCUIT.
Check stop light switch open circuit.
Is the stop light switch circuit
OK?
Go to step 2.
Repair the stop
light switch circuit.
NOTE:
If there is malfunc-
tion in the stop light
circuit, DTC may
be memorized.
2
CHECK OUTPUT OF PRESSURE SENSOR
WITH SUBARU SELECT MONITOR.
1) Select {Current Data Display & Save} in
Subaru Select Monitor.
2) Read the pressure sensor output displayed
on display.
When the brake pedal is
released, is the displayed value
–40 — 40 bar?
Go to step 3.
Replace the
VDCCM&H/U.
<Ref. to VDC-7,
VDC Control Mod-
ule and Hydraulic
Control Unit
(VDCCM&H/U).>
3
CHECK OUTPUT OF PRESSURE SENSOR
WITH SUBARU SELECT MONITOR.
1) Select {Current Data Display & Save} in
Subaru Select Monitor.
2) Read the pressure sensor output displayed
on display.
When operating the brake
pedal, does the pressure sen-
sor output value on the display
change according to the brake
pedal operation?
Go to step 4.
Replace the
VDCCM&H/U.
<Ref. to VDC-7,
VDC Control Mod-
ule and Hydraulic
Control Unit
(VDCCM&H/U).>
4
CHECK PRESSURE SENSOR.
1) Clear the memory. <Ref. to VDC(diag)-23,
Clear Memory Mode.>
2) Perform the Inspection Mode. <Ref. to
VDC(diag)-22, Inspection Mode.>
3) Read the DTC.
Is the same DTC displayed?
Replace the
VDCCM&H/U.
<Ref. to VDC-7,
VDC Control Mod-
ule and Hydraulic
Control Unit
(VDCCM&H/U).>
Go to step 5.
5
CHECK OTHER DTC DETECTION.
Is any other DTC displayed?
Perform the diag-
nosis according to
DTC. <Ref. to
VDC(diag)-34, List
of Diagnostic Trou-
ble Code (DTC).>
It results from a
temporary noise
interference.
VDC(diag)-100
Diagnostic Procedure with Diagnostic Trouble Code (DTC)
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
BA:DTC C0081 SYSTEM FAILURE
DTC DETECTING CONDITION:
VDC long time sequential control
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
Step
Check
Yes
No
1
CHECK POOR CONTACT IN CONNECTOR.
Is there poor contact in the
VDCCM& H/U and yaw rate &
lateral G sensor connector?
Repair the connec-
tor.
Go to step 2.
2
CHECK VDCCM&H/U.
1) Replace the yaw rate & lateral G sensor.
2) Connect all connectors.
3) Clear the memory. <Ref. to VDC(diag)-23,
Clear Memory Mode.>
4) Perform the Inspection Mode. <Ref. to
VDC(diag)-22, Inspection Mode.>
5) Read the DTC.
Is the same DTC displayed?
Replace the
VDCCM&H/U.
Malfunction is
found in original
yaw rate & lateral
G sensor.
VDC(diag)-101
General Diagnostic Table
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
13.General Diagnostic Table
A: INSPECTION
Symptom
Main probable cause
Other probable cause
Poor brake perfor-
mance
Long braking/
stopping dis-
tance
• VDCCM&H/U
• Brake pad
• Aeration to brake line
• Tire specifications, tire wear and air pressures
• Incorrect wiring or piping connections
• Defective ABS wheel speed sen-
sor or sensor gap
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
• Master cylinder
• Brake caliper
• Disc rotor
• Brake pipe
• Brake booster
Wheel locks.
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Incorrect wiring or piping connections
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
• Brake caliper
• Brake pipe
Brake drag
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Master cylinder
• Brake caliper
• Parking brake
• Axle and wheels
• Brake pedal play
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
• Brake pad
• Brake pipe
Long brake
pedal stroke
• Aeration to brake line
• Brake pedal play
• VDCCM&H/U
• Master cylinder
• Brake caliper
• Brake pad
• Brake pipe
• Brake booster
Vehicle vertical
pitching
• VDCCM&H/U
• Road surface (uneven)
• Suspension play or fatigue (reduced damping)
• Incorrect wiring or piping connections
• Defective ABS wheel speed sen-
sor or sensor gap
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
Poor brake perfor-
mance
Unstable or
uneven brak-
ing
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Brake caliper
• Brake pad
• Road surface (uneven)
• Tire specifications, tire wear and air pressures
• Incorrect wiring or piping connections
• Defective ABS wheel speed sen-
sor or sensor gap
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
• Master cylinder
• Disc rotor
• Brake pipe
• Axle and wheels
• Road with crowns or banks
• Suspension play or fatigue
(reduced damping)
VDC(diag)-102
General Diagnostic Table
VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)
Vibration or noise
• When braking
suddenly
• When accelerat-
ing suddenly
• While driving on a
slippery road
Excessive
brake pedal
vibration
• Road surface (uneven)
• Incorrect wiring or piping connections
• VDCCM&H/U
• Brake booster
• Suspension play or fatigue
(reduced damping)
Noise from
VDCH/U
• VDCCM&H/U (mount bushing)
• Defective ABS wheel speed sensor or sensor gap
• Brake pipe
• VDCCM&H/U
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
Noise from the
front side of
vehicle
• VDCCM&H/U (mount bushing)
• Defective ABS wheel speed sensor or sensor gap
• Master cylinder
• Brake caliper
• Brake pad
• Disc rotor
• Brake pipe
• Brake booster
• Suspension play or fatigue (reduced damping)
• Axle and wheels
• Tire specifications, tire wear and
air pressures
Noise from the
rear side of
vehicle
• Defective ABS wheel speed sensor or sensor gap
• Brake caliper
• Brake pad
• Disc rotor
• Parking brake
• Brake pipe
• Suspension play or fatigue (reduced damping)
• Axle and wheels
• Tire specifications, tire wear and
air pressures
Engine does not accelerate or goes
into a stall when accelerating sud-
denly or driving on a slippery surface.
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Master cylinder
• Brake caliper
• Parking brake
• Incorrect wiring or piping
• Defective steering angle sensor
or improper neutral position
• Defective yaw rate & lateral G
sensor or improper installation
• Brake pad
• Brake pipe
Poor change-direc-
tion-operation sta-
bility of TCS
Deviation to
right or left
direction
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Defective steering angle sensor or improper neu-
tral position
• Defective yaw rate & lateral G sensor or improper
installation
• Brake caliper
• Brake pad
• Wheel alignment
• Road surface (uneven)
• Road with crowns or banks
• Tire specifications, tire wear and air pressures
• Incorrect wiring or piping connections
• Disc rotor
• Brake pipe
• Axle and wheels
• Suspension play or fatigue
(reduced damping)
Vehicle spin
• VDCCM&H/U
• Defective ABS wheel speed sensor or sensor gap
• Defective steering angle sensor or improper neu-
tral position
• Defective yaw rate & lateral G sensor or improper
installation
• Brake pad
• Tire specifications, tire wear and air pressures
• Incorrect wiring or piping connections
• Brake caliper
• Brake pipe
Symptom
Main probable cause
Other probable cause
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