Subaru Legacy IV (2008 year). Service manual — part 912

ABS(diag)-47

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

S: DTC C0109 POWER VOLTAGE MALFUNCTION

DTC DETECTING CONDITION:
Power supply voltage of the ABSCM&H/U is too low or too high.
TROUBLE SYMPTOM:
• ABS does not operate.
• EBD may not operate.

NOTE:
If EBD does not operate, the brake warning light illuminates in addition to ABS warning light. Both warning
lights go off if voltage returns.
WIRING DIAGRAM:

ABS00805

MAIN SBF

SBF-6

No.33

B301

E

E

15

18

ABSCM & H/U

BATTERY

GENERATOR

IGNITION
SWITCH

B301

1 2 3 4 5 6 7 8 9 10 11

16 17 18 19 20 21 22 23 24 25 26

13

12

15

14

ABS(diag)-48

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

Step

Check

Yes

No

1

CHECK GENERATOR.
1) Start the engine.
2) Run the engine at idle after warming up.
3) Measure the voltage between generator ter-
minal B and chassis ground.

Terminals

Generator B terminal (+) — Chassis
ground (–):

Is the voltage 10 — 15 V?

Go to step 2.

Repair the genera-
tor.

2

CHECK BATTERY TERMINAL.
Turn the ignition switch to OFF.

Are the positive and negative
battery terminals tightened
securely?

Go to step 3.

Tighten the termi-
nal.

3

CHECK INPUT VOLTAGE OF ABSCM&H/U.
1) Disconnect the ABSCM&H/U connectors.
2) Run the engine at idle.
3) Operate devices such as headlights, air
conditioner, defogger, etc. which produce an
electrical load.
4) Measure the voltage between ABSCM&H/U
connector and chassis ground.

Connector & terminal

(B301) No. 18 (+) — Chassis ground (–):

Is the voltage 10 — 15 V?

Go to step 4.

Repair the
ABSCM&H/U
power circuit.

4

CHECK THE ABSCM&H/U GROUND CIR-
CUIT.
1) Turn the ignition switch to OFF.
2) Measure the resistance between the
ABSCM&H/U connector and chassis ground.

Connector & terminal

(B301) No. 15 — Chassis ground:

Is the resistance less than 0.5

:? Go to step 5.

Repair the
ABSCM&H/U
ground harness.

5

CHECK POOR CONTACT IN CONNECTOR.

Is there poor contact in connec-
tor between generator, battery
and ABSCM&H/U?

Repair the connec-
tor.

Go to step 6.

6

CHECK ABSCM&H/U.
1) Connect all connectors.
2) Clear the memory. <Ref. to ABS(diag)-20,
Clear Memory Mode.>
3) Perform the Inspection Mode. <Ref. to
ABS(diag)-19, Inspection Mode.>
4) Read the DTC.

Is the same DTC displayed?

Replace the
ABSCM only. <Ref.
to ABS-8,
REPLACEMENT,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

Go to step 7.

7

CHECK FOR ANY OTHER DTC ON DISPLAY. Is any other DTC displayed?

Check DTC using
“List of Diagnostic
Trouble Code
(DTC)”. <Ref. to
ABS(diag)-29, List
of Diagnostic Trou-
ble Code (DTC).>

Temporary poor
contact occurs.

ABS(diag)-49

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

T: DTC C0140 CAN COMMUNICATION MALFUNCTION

DTC DETECTING CONDITION:
Defective CAN communication
TROUBLE SYMPTOM:
Possibly the vehicle speed cannot output on CAN.

Step

Check

Yes

No

1

CHECK LAN SYSTEM.
Perform the diagnosis for LAN system. <Ref. to
LAN(diag)-27, OPERATION, Read Diagnostic
Trouble Code (DTC).>

Is there any fault in LAN sys-
tem?

Repair it according
to DTC of LAN sys-
tem.

Replace the
ABSCM only. <Ref.
to ABS-8,
REPLACEMENT,
ABS Control Mod-
ule and Hydraulic
Control Unit
(ABSCM&H/U).>

ABS(diag)-50

Diagnostic Procedure with Diagnostic Trouble Code (DTC)

ABS (DIAGNOSTICS)

U: DTC C0114 VALVE RELAY MALFUNCTION

DTC DETECTING CONDITION:
Defective valve relay
TROUBLE SYMPTOM:
• ABS does not operate.
• EBD does not operate depending on the trouble contents.

NOTE:
Brake warning light illuminates as well as ABS warning light when EBD does not operate.
WIRING DIAGRAM:

B301

B301

E

14

15

ABSCM & H/U

18

M

F

L

INLET

MAIN SBF

SBF-6

No.1

No.33

E

F

R

INLET

R

L

INLET

R

R

INLET

FL OUTLET

FR OUTLET

RL OUTLET

RR OUTLET

4 5 6 7 8 9

16 17 18 19 20

2 3

1

21 22 23 24 25 26

10 11

13

14

12

15

ABS00996

BATTERY

IGNITION
SWITCH

MO

T

OR RELA

Y

VALVE RELAY

SOLENOID V

A

L

V

E

PUMP MOTOR