Mitsubishi Evolution X. Manual - part 581

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-231

STEP 2. Check KOS-ECU connector C-05 and trunk lid 
opener switch connector F-09 for loose, corroded or 
damaged terminals, or terminals pushed back in the 
connector.
Q: Are KOS-ECU connector C-05 and trunk lid opener 

switch connector F-09 in good condition?
YES : Go to Step 3.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Check that the trunk lid opener switch works 

normally.

STEP 3. Check the trunk lid opener switch.
(1) Remove the trunk lid opener switch. Refer to GROUP 42A, 

Trunk Lid 

P.42A-147

.

(2) Check continuity when the trunk lid opener switch is 

operated to "ON" or "OFF" position.

Q: Is the trunk lid opener switch normal?

YES : Go to Step 4.
NO :  Replace the trunk lid opener switch.

Switch 
position

Terminal 
number

Specified 
condition

ON (Push)

1 

− 2

Continuity 
exists (2 

Ω or 

less)

OFF (Release)

1 

− 2

Open circuit

AC607401AB

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-232

STEP 4. Check the wiring harness between the KOS-ECU 
connector C-05 (terminal No. 28) and trunk lid opener 
switch connector F-09 (terminal No. 1), and between trunk 
lid opener switch connector F-09 (terminal No. 2) and 
ground for open circuit.
(1) Disconnect KOS-ECU connector C-05 and trunk lid opener 

switch connector F-09, and check the wiring harness.

(2) Check the wiring harness between KOS-ECU connector 

C-05 (terminal No.28) and trunk lid opener switch connector 
F-09 (terminal No.1).

OK: Continuity exists (2 

Ω or less)

(3) Check the wiring harness between trunk lid opener switch 

connector F-09 (terminal No.2) and ground.

OK: Continuity exists (2 

Ω or less)

Q: Is the wiring harness between KOS-ECU connector C-05 

(terminal No. 28) and trunk lid opener switch connector 
F-09 (terminal No. 1), and between trunk lid opener 
switch connector F-09 (terminal No. 2) and ground in 
good condition?
YES  : Go to Step 5.
NO (KOS-ECU connector C-05 terminal No.28 

− trunk lid 

opener switch connector F-09 terminal No.1.) : Repair 

the wiring harness between KOS-ECU connector 
C-05 (terminal No.28) and trunk lid opener switch 
connector F-09 (terminal No.1).

NO (trunk lid opener switch connector F-09 terminal 
No.2 

− ground.) : Repair the wiring harness between trunk 

lid opener switch connector F-09 (terminal No.2) and 
ground.

AC709707GY

Harness side: F-09

Harness side: C-05

AC209731

Connector F-09 
(harness side)

AC208731CJ

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-233

STEP 5. Check the wiring harness between the trunk lid 
opener switch connector F-09 (terminal Nos. 1, 2) and the 
ground for short circuit.
(1) Disconnect trunk lid opener switch connector F-09, and 

check the wiring harness.

(2) Check the wiring harness between trunk lid opener switch 

connector F-09 (terminal No. 1) and ground

OK: No continuity

(3) Check the wiring harness between trunk lid opener switch 

connector F-09 (terminal No. 2) and ground

OK: No continuity

Q: Is the wiring harness between trunk lid opener switch 

connector F-09 (terminal Nos. 1, 2) and the ground in 
good condition?
YES  : Go to Step 6.
NO (trunk lid opener switch connector F-09 terminal 
No.1 

− ground.) : Repair the wiring harness between trunk 

lid opener switch connector F-09 (terminal No.1) and 
ground.

NO (trunk lid opener switch connector F-09 terminal 
No.2 

− ground.) : Repair the wiring harness between trunk 

lid opener switch connector F-09 (terminal No.2) and 
the ground.

STEP 6. KOS communication test
Using scan tool (M.U.T.-III), perform the antenna communica-
tion test to check that the exterior transmitter antenna (trunk lid 
side) is normal (Refer to 

P.42B-265

).

Q: Is the check result normal?

YES : Go to Step 7.
NO :  Perform troubleshooting for the diagnostic trouble 

code No. B240C (Refer to 

P.42B-84

).

STEP 7. Check of the troubles
Operate the trunk lid opener switch to check that the trunk lid 
can be opened.
Q: Is the check result normal?

YES : The diagnosis is complete.
NO :  Replace KOS-ECU and register the ID codes (Refer 

to 

P.42B-12

).

AC209731

AC208731CR

Harness side: F-09

AC209731

AC208731CS

Harness side: F-09

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-234

Inspection Procedure 14: Keyless entry system does not work.

CAUTION

Before replacing the ECU, ensure that the power 
supply circuit, the ground circuit and the com-
munication circuit are normal.

AC709247

JOINT 
CONNECTOR (6)

RECEIVER

KEYLESS 
OPERATION 
KEY

KOS-ECU

KOS-ECU System Input Signal

RECEIVER 
ANTENNA 
ASSEMBLY

AB

RED

RED

GREEN -RED

GREEN -RED

YELLOW

-GREEN

YELLOW

-GRAY

YELLOW

-GRAY

BROWN -WHITE

BROWN -WHITE

RED- WHITE

RED- WHITE

RED

GREEN -RED

BROWN -WHITE

RED- WHITE

AC708950AX

C-41

Connectors: C-05, C-41

C-05

AC708951AW

Connector: C-16

C-16 (B)