Subaru Legacy (2005 year). Manual - part 816

VDC(diag)-129

VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

2

CHECK PRESSURE SENSOR POWER SUP-
PLY.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from pressure 
sensor.
3) Turn the ignition switch to ON.
4) Measure the voltage between pressure 
sensor connector and chassis ground.

Connector & terminal

(B348) No. 3 (+) — Chassis ground (

−

):

Is the voltage 4.75 — 5.25 V?

Go to step 5.

Go to step 3.

3

CHECK OUTPUT VOLTAGE OF VDCCM&H/
U.
Measure the voltage between VDCCM&H/U 
and chassis ground.

Connector & terminal

(B310) No. 27 (+) — Chassis ground (

−

):

Is the voltage 4.75 — 5.25 V?

Repair the har-
ness between 
pressure sensor 
and VDCCM&H/U.

Go to step 4.

4

CHECK POOR CONTACT IN CONNECTORS. Is there poor contact in con-

nector?

Correct or replace 
the connector.

Go to step 10.

5

CHECK GROUND CIRCUIT OF PRESSURE 
SENSOR.
Measure the resistance between pressure 
sensor and chassis ground.

Connector & terminal

(B348) No. 1 — Chassis ground:

Is the resistance less than 0.5 
Ω?

Go to step 8.

Go to step 6.

6

CHECK GROUND CIRCUIT OF VDCCM&H/U.
Measure the resistance between VDCCM&H/U 
and chassis ground.

Connector & terminal

(B310) No. 12 — Chassis ground:

Is the resistance less than 0.5 
Ω?

Repair the har-
ness between 
pressure sensor 
and VDCCM&H/U.

Go to step 7.

7

CHECK POOR CONTACT IN CONNECTORS. Is there poor contact in con-

nector?

Correct or replace 
the connector.

Go to step 10.

8

CHECK PRESSURE SENSOR HARNESS.
1) Turn the ignition switch to OFF.
2) Disconnect the connector from VDCCM&H/
U.
3) Measure the resistance between 
VDCCM&H/U and pressure sensor.

Connector & terminal

(B310) No. 11 — (B348) No. 2:

Is the resistance less than 0.5 
Ω?

Go to step 9.

Repair the har-
ness between 
pressure sensor 
and VDCCM&H/U.

9

CHECK GROUND SHORT OF HARNESS.
Measure the resistance between VDCCM&H/U 
connector and chassis ground.

Connector & terminal

(B310) No. 11 — Chassis ground:

Is the resistance more than 1 
M

Ω?

Go to step 10.

Repair the har-
ness between 
pressure sensor 
and VDCCM&H/U.

10

CHECK VDCCM&H/U.
1) Connect all the connectors.
2) Perform the clear memory mode.
3) Perform the inspection mode.
4) Read the DTC.

Is 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 11.

11

CHECK OTHER DTC DETECTION.

Is any other DTC displayed?

Perform the diag-
nosis according to 
DTC.

Temporary poor 
contact occurs.

Step

Check

Yes

No

VDC(diag)-130

VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BK:DTC C0074 PRESSURE SENSOR POWER MALFUNCTION

DTC DETECTING CONDITION:
Defective pressure sensor
TROUBLE SYMPTOM:
• ABS does not operate.
• VDC does not operate.
WIRING DIAGRAM:

VDC00309

MAIN SBF

SBF-6

No.33

B310

B310

E

E

6

14

VDCCM & H/U

1 2 3 4

11 12 13 14
27 28 29 30

15 16 17 18
31 32 33 34

19 20 21 22
35 36 37 38

23 24 25 26
39 40 41 42

5

6

7

8

9

10

BATTERY

GENERATOR

IGNITION
SWITCH

VDC(diag)-131

VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

BL:DTC C0081 SYSTEM MALFUNCTION

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 CONNECTORS.
Check if there is poor contact in VDCCM&H/U 
power supply circuit.

Is there poor contact?

Repair the con-
nector.

Go to step 2.

2

CHECK VDCCM&H/U POWER SUPPLY CIR-
CUIT.
1) Turn the ignition switch to OFF.
2) Disconnect the VDCCM&H/U connector.
3) Turn the ignition switch to ON.
4) Measure the voltage between VDCCM&H/
U connector terminals.

Connector & terminal

(B310) No. 14 (+) — (B310) No. 6 (

−

):

Is the voltage 10 — 15 V?

Go to step 3.

Check the power 
supply circuit in 
VDCCM&H/U.

3

CHECK VDCCM&H/U.
1) Connect all the connectors.
2) Perform the clear memory mode.
3) Perform the inspection mode.
4) 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 4.

4

CHECK OTHER DTC DETECTION.

Is any other DTC displayed?

Perform the diag-
nosis according to 
DTC.

It results from a 
temporary noise 
interference.

Step

Check

Yes

No

1

CHECK POOR CONTACT IN CONNECTOR. Is there poor contact in the 

VDCCM&H/U connector and 
yaw rate & lateral G sensor 
connector?

Repair the con-
nector.

Go to step 2.

2

CHECK VDCCM&H/U.
1) Replace the yaw rate & lateral G sensor.
2) Connect all the connectors.
3) Perform the clear memory mode.
4) Perform the 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)-132

VEHICLE DYNAMICS CONTROL (VDC) (DIAGNOSTICS)

General Diagnostic Table

13.General Diagnostic Table

A: INSPECTION

Symptom

Main probable cause

Other probable cause

Poor brake per-
formance

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 sensor 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 lock

• 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 sensor or sensor 
gap
• Defective steering angle sensor or improper 
neutral position
• Defective yaw rate & lateral G sensor or 
improper installation

Poor brake per-
formance

Unstable or 
uneven braking

• 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 sensor 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 (poor damping)