Subaru Impreza 3 / Impreza WRX / Impreza WRX STI. Manual — part 447

6MT-125

General Diagnostic Table

MANUAL TRANSMISSION AND DIFFERENTIAL

2. DIFFERENTIAL

Symptoms

Possible cause

Corrective action

1. Broken differential (case, gear, bearing,
etc.)
NOTE:

Noise will occur, and eventually the differ-
ential will not be able to operate due to bro-
ken pieces obstructing the gear revolution.

(a) Insufficient or improper oil

Disassemble the differential and
replace broken components. At the
same time check other components for
any trouble, and replace if necessary.

(b) Use of vehicle under severe conditions
such as excessive load and improper use
of the clutch

Readjust the preload and backlash of
the bearing, and the contact surface of
gear.

(c) Improper adjustment of taper roller
bearing

Adjust.

(d) Improper adjustment of the drive pinion
and the hypoid driven gear

Adjust.

(e) Loose hypoid driven gear clamping
bolts

Tighten.

2. Differential and hypoid gear noise
Troubles of the differential and hypoid gear
always appear as noise problems. There-
fore noise is the first indication of trouble.
However, noise from the engine, muffler,
tire, exhaust gas, bearing, body, etc. are
easily mistaken for noise from the differen-
tial. Pay special attention to the hypoid
gear noise because it is easily confused
with other gear noises. There are the fol-
lowing four kinds of noises.
• Gear noise when driving: If noise
increases as the vehicle speed increases,
it may be due to insufficient gear oil, incor-
rect gear engagement, damaged gears,
etc.
• Gear noise during coasting: Damaged
gears due to misadjusted bearings and
incorrect shim adjustment.
• Bearing noise when driving or coasting:
Cracked, broken or damaged bearings.

(a) Insufficient oil

Replenish or replace with the specified
amount of recommended oil.

(b) Improper adjustment of hypoid driven
gear and drive pinion

Check the tooth contact.

(c) Worn teeth of hypoid driven gear and
drive pinion

Replace as a set.
Readjust the bearing preload.

(d) Loose roller bearing

Readjust the backlash of the hypoid
driven gear to drive pinion, and check
the tooth contact.

(e) Distorted hypoid driven gear or differen-
tial case

Replace.

6MT-126

General Diagnostic Table

MANUAL TRANSMISSION AND DIFFERENTIAL

MANUAL TRANSMISSION AND DIFFEREN-

TIAL (DIAGNOSTICS)

6MT(diag)

Page

1.

Basic Diagnostic Procedure . . . . . . . . . . . . . . . . . ...2

2.

Check List for Interview . . . . . . . . . . . . . . . . . . . ..3

3.

General Description . . . . . . . . . . . . . . . . . . . . ...4

4.

Electrical Component Location . . . . . . . . . . . . . . . . ..5

5.

Driver’s Control Center Differential (DCCD) Control Module I/O Signal . 8

6.

Subaru Select Monitor . . . . . . . . . . . . . . . . . . . ..10

7.

Read Current Data . . . . . . . . . . . . . . . . . . . . ...11

8.

Read Diagnostic Trouble Code (DTC) . . . . . . . . . . . . . .12

9.

Clear Memory Mode . . . . . . . . . . . . . . . . . . . . .13

10.

Driver’s Control Center Differential (DCCD) Manual Mode Display . . .14

11.

Diagnostic Procedure for Subaru Select Monitor Communication . . ...16

12.

List of Diagnostic Trouble Code (DTC) . . . . . . . . . . . . . 19

13.

Diagnostic Procedure with Diagnostic Trouble Code (DTC) . . . . . 20

14.

Diagnostic Procedure without Diagnostic Trouble Code (DTC) . . . ...28

15.

Diagnostics with Phenomenon . . . . . . . . . . . . . . . . .34

6MT(diag)-2

Basic Diagnostic Procedure

MANUAL TRANSMISSION AND DIFFERENTIAL (DIAGNOSTICS)

1. Basic Diagnostic Procedure

A: PROCEDURE

Step

Check

Yes

No

1

START INSPECTIONS.
1) Use the Check List for Interview to confirm
the condition of the problem from the user.
<Ref. to 6MT(diag)-3, Check List for Interview.>
2) Check the items related to DCCD.
• General inspection <Ref. to 6MT(diag)-4,
INSPECTION, General Description.>
• Disconnection of harness connector
• Visual check for harness connector damage
• Oil leakage

Are items related to DCCD OK? Go to step

2.

Repair the defec-
tive items.

2

CHECK DTC.
Read the DTC. <Ref. to 6MT(diag)-10, Subaru
Select Monitor.>
NOTE:

• Refer to “List of Diagnostic Trouble Code
(DTC)” for DTC. <Ref. to 6MT(diag)-19, List of
Diagnostic Trouble Code (DTC).>
• If the communication function of Subaru Se-
lect Monitor cannot be executed normally,
check communication circuit. <Ref. to 6MT(di-
ag)-10, Subaru Select Monitor.>

Is DTC displayed?

Record all DTC.
Go to step

3.

Inspect based on
the general diag-
nosis table. <Ref.
to 6MT(diag)-34,
Diagnostics with
Phenomenon.>

3

CHECK FREEZE FRAME DATA.
Using the Subaru Select Monitor, check the
Freeze Frame Data.

Are freeze frame data
recorded?

Record the Freeze
Frame Data.
Go to step

4.

Go to step

4.

4

PERFORM DIAGNOSIS.
1) Inspect and repair all DTC using the “Diag-
nostic Procedure with Diagnostic Trouble Code
(DTC)”. <Ref. to 6MT(diag)-20, Diagnostic Pro-
cedure with Diagnostic Trouble Code (DTC).>
NOTE:

Refer to “List of Diagnostic Trouble Code
(DTC)” for DTC. <Ref. to 6MT(diag)-19, List of
Diagnostic Trouble Code (DTC).>
2) Start the engine.
3) Read the DTC using Subaru Select Monitor.
<Ref. to 6MT(diag)-10, Subaru Select Monitor.>

Is DTC displayed?

Record all DTC
using the “Diag-
nostic Procedure
with Diagnostic
Trouble Code
(DTC)” for the
inspection. <Ref.
to 6MT(diag)-20,
Diagnostic Proce-
dure with Diagnos-
tic Trouble Code
(DTC).> Repeat
execute diagnosis
until DTC no longer
appears.

Inspect based on
the general diag-
nosis table. <Ref.
to 6MT(diag)-34,
Diagnostics with
Phenomenon.>