Subaru Legacy IV (2008 year). Manual - part 1167

LAN(diag)-2

Basic Diagnostic Procedure

LAN SYSTEM (DIAGNOSTICS)

1. Basic Diagnostic Procedure

A: PROCEDURE

CAUTION:
• Subaru Select Monitor is required for reading DTC, performing diagnosis and reading current data.
• Remove foreign matter (dust, water, oil, etc.) from the body integrated unit connector during re-
moval and installation.
• For model with immobilizer, registration of immobilizer may be needed after the replacement of
controller etc. For details, refer to the “PC application help for Subaru Select Monitor”.

NOTE:
• To check harness for open or short circuits, shake the suspected trouble spot or connector.
• Check List for Interview <Ref. to LAN(diag)-3, Check List for Interview.>

Step

Check

Yes

No

1

CHECK PRE-INSPECTION.
Ask the customer when and how the trouble 
occurred using the interview check list. <Ref. to 
LAN(diag)-3, Check List for Interview.>

Did you interview the cus-
tomer?

Go to step 2.

Interview the cus-
tomer and Go to 
step 2.

2

BASIC INSPECTION.
Check the components which might affect body 
control. <Ref. to LAN(diag)-5, INSPECTION, 
General Description.>

Is the component that might 
influence the body control prob-
lem normal?

Go to step 3.

Repair or replace 
each component.

3

CHECK INDICATION OF DTC.
1) Read the DTC. <Ref. to LAN(diag)-12, 
READ DIAGNOSTIC TROUBLE CODE (DTC), 
OPERATION, Subaru Select Monitor.>

NOTE:
If the communication function of the Subaru Se-
lect Monitor cannot be executed properly,
check the communication circuit. <Ref. to
LAN(diag)-24, COMMUNICATION FOR INI-
TIALIZING IMPOSSIBLE, INSPECTION, Sub-
aru Select Monitor.>
2) Record all DTC.

Is DTC displayed?

Go to step 5.

Go to step 4.

4

PERFORM GENERAL DIAGNOSTICS.
Inspect using the “General Diagnostics Table”. 
<Ref. to LAN(diag)-83, General Diagnostic 
Table.>

Is result of inspection OK?

LAN system is nor-
mal.

Go to step 5.

5

PERFORM DIAGNOSIS.
1) Correct the cause of trouble.
2) Perform the Clear Memory Mode. <Ref. to 
LAN(diag)-20, CLEAR MEMORY MODE, 
OPERATION, Subaru Select Monitor.>
3) Read the DTC. <Ref. to LAN(diag)-12, 
READ DIAGNOSTIC TROUBLE CODE (DTC), 
OPERATION, Subaru Select Monitor.>

Is DTC displayed?

Repeat step 5 until 
DTC is not shown.

Finish the diagno-
sis.

LAN(diag)-3

Check List for Interview

LAN SYSTEM (DIAGNOSTICS)

2. Check List for Interview

A: CHECK

Inspect the following item about the vehicle’s state.

1. DISPLAY OF COMMUNICATION ERROR

2. DISPLAY STATUS IN THE COMBINATION METER

3. SYMPTOM

Communication error is 
displayed in odo/trip meter. 
(Except for meter with 
MID)

When and how often are they displayed?

 Always
 Sometimes
 Only once

Which communication error is displayed? (Record them all)

 Er IU (Fail in the body integrated unit)
 Er HC (Fail of high-speed CAN)
 Er LC (Fail of low-speed CAN)
 Er –– (Fails of both high-speed and low-speed CAN)
 Er EG (Fail of EGI communication data)
 Er TC (fail of TCM communication data)
 Er Ab (Fail of vehicle dynamics control (VDC)/ABS communication data)

Ignition key position

 OFF
 ACC
 ON (before starting engine)
 START
 ON (after starting engine, engine is running)
 ON (after starting engine, engine is at a standstill)

Timing

 Immediately after turning the ignition ON.
 Immediately after turning the ignition to START.

Display status in the com-
bination meter

a) Engine coolant temperature gauge display

 OK / 

 NG

b) Fuel gauge display

 OK / 

 NG

Display of other indicators

c) Malfunction indicator light

 ON / 

 OFF

d) SPORT indicator light (AT warning light)

 ON / 

 OFF

e) ABS warning light/Vehicle dynamics control (VDC) warning 
light

 ON / 

 OFF

f) Security indicator light

 ON / 

 Blink / 

 OFF

g) Seat belt warning light (Driver’s seat)

 ON / 

 OFF

h) Seat belt warning light (Passenger’s seat)

 ON / 

 OFF

Vehicle condition

a) Lighting adjustment is not possible by the illumination volume 
control.

 Yes / 

 No

b) Rear wiper does not operate.

 Yes / 

 No

c) Wiper deicer does not operate.

 Yes / 

 No

d) Rear defogger does not operate.

 Yes / 

 No

e) Door lock does not operate.

 Yes / 

 No

f) Trunk/rear gate lock does not operate.

 Yes / 

 No

g) Drivers door lock does not operate.

 Yes / 

 No

h) Shift lock does not operate.

 Yes / 

 No

i) Key illumination blinks.

 Yes / 

 No

LAN(diag)-4

Check List for Interview

LAN SYSTEM (DIAGNOSTICS)

4. CONDITIONS UNDER WHICH TROUBLE OCCURS

Driving condition

 At standstill (While idling)

 When the vehicle is running

Vehicle speed km/h (MPH)

 While accelerating

Acceleration    km/h (MPH) to    km/h (MPH)

 Decelerating (With braking)

Deceleration    km/h (MPH) to    km/h (MPH)

 Decelerating (Without braking) Deceleration    km/h (MPH) to    km/h (MPH)

 Flat road
 Uphill
 Downhill
 Gravel road
 Bumpy road
 Snowy road

Does it occur when operating any part?
Operated part:
Trouble symptom:

Are there any other troubles occurred?
From where:
Trouble symptom:

LAN(diag)-5

General Description

LAN SYSTEM (DIAGNOSTICS)

3. General Description

A: CAUTION

1. SUPPLEMENTAL RESTRAINT SYSTEM 
“AIRBAG”

Airbag system wiring harness is routed near the
body integrated unit and twisted pair line.

CAUTION:
• Do not use electrical test equipment on any
airbag system wiring harness and connector
circuit.
• Be careful not to damage the airbag system
wiring harness when servicing the body inte-
grated unit and LAN system.

2. LAN SYSTEM

• Bus line of LAN system is twisted pair line. Be
careful not to by-pass or partly unbind the twisted
pair line.
• Do not make clearance between bus lines (CAN
High, CAN Low).
• Difference of bus line length should be within 10
cm (3.94 in).
• Fray near the connector should be within 8 cm
(3.14 in).

• If the characteristics of the twisted pair line are
changed, it may extremely weaken against noise.
• When repairing the harness, connect the wires
using soldering and protect it with insulating tape
etc.

B: INSPECTION

Before performing diagnostics, check the following
item which might affect body integrated unit mal-
functions.
1) Measure the battery voltage and check electro-
lyte.

Standard voltage: 12 V or more

Specific gravity: Above 1.260
2) Check the fuse condition.
Make sure that ampere of the fuse is setting value,
and it is not blown out. While doing this, also check
the backup fuse condition.
3) Check the connecting condition of harness and
harness connector.
4) Confirm that a setting that does not match the
vehicle equipment, is not set in the body integrated
unit. <Ref. to LAN(diag)-18, REGISTRATION
BODY INTEGRATED UNIT (EQUIPMENT SET-
TING), OPERATION, Subaru Select Monitor.>
5) Make sure that the function setting (ECM cus-
tomizing) of the body integrated unit matches the
vehicle equipment. <Ref. to LAN(diag)-21, FUNC-
TION SETTING (ECM CUSTOMIZING), OPERA-
TION, Subaru Select Monitor.>
6) Confirm “Factory or Market setting” of body inte-
grated unit registrations is “Market”.
7) Confirm key illumination does not blink with igni-
tion switch turned to ON.

(A) Bypass wire connection

(A) Soldering and protection with insulating tape

LAN00225

(A)

LAN00224

(A)