Mitsubishi Evolution X. Manual - part 545

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-87

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

C-05 (terminal No.40) and outside transmitter antenna 
assembly (trunk lid) connector F-20 (terminal No.3).

OK: Continuity exists (2 

Ω or less)

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

(terminal Nos. 6, 19, 40) and outside transmitter antenna 
assembly (trunk lid) connector F-20 (terminal Nos. 1, 2, 
3) in good condition?
YES  : Go to Step 3.
NO (KOS-ECU connector C-05 terminal No.6 

− outside 

transmitter antenna assembly (trunk lid) connector F-20 
terminal No.1.) : Repair the wiring harness between 

KOS-ECU connector C-05 (terminal No.6) and 
outside transmitter antenna assembly (trunk lid) 
connector F-20 (terminal No.1).

NO (KOS-ECU connector C-05 terminal No.19 

− outside 

transmitter antenna assembly (trunk lid) connector F-20 
terminal No.2.) : Repair the wiring harness between 

KOS-ECU connector C-05 (terminal No.19) and 
outside transmitter antenna assembly (trunk lid) 
connector F-20 (terminal No.2).

NO (KOS-ECU connector C-05 terminal No.40 

− outside 

transmitter antenna assembly (trunk lid) connector F-20 
terminal No.2.) : Repair the wiring harness between 

KOS-ECU connector C-05 (terminal No.40) and 
outside transmitter antenna assembly (trunk lid) 
connector F-20 (terminal No.2).

AC709707FI

Harness side: F-20

Harness side: C-05

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-88

STEP 3. Check the wiring harness between the outside 
transmitter antenna assembly (trunk lid) connector F-20 
(terminal Nos. 1, 2, 3) and the ground for short circuit.
(1) Disconnect outside transmitter antenna assembly (trunk lid) 

connector F-20, and check the wiring harness.

(2) Check the wiring harness between outside transmitter 

antenna assembly (trunk lid) connector F-20 (terminal No.1) 
and ground

OK: No continuity

(3) Check the wiring harness between outside transmitter 

antenna assembly (trunk lid) connector F-20 (terminal No.2) 
and ground

OK: No continuity

(4) Check the wiring harness between outside transmitter 

antenna assembly (trunk lid) connector F-20 (terminal No.3) 
and ground

OK: No continuity

Q: Is the wiring harness between outside transmitter 

antenna assembly (trunk lid) connector F-20 (terminal 
Nos. 1, 2, 3) and the ground in good condition?
YES  : Go to Step 4.
NO [outside transmitter antenna assembly (trunk lid) 
connector F-20 terminal No.1 

− ground.] : Repair the 

wiring harness between outside transmitter antenna 
assembly (trunk lid) connector F-20 (terminal No.1) 
and ground.

NO [outside transmitter antenna assembly (trunk lid) 
connector F-20 terminal No.2 

− ground.] : Repair the 

wiring harness between outside transmitter antenna 
assembly (trunk lid) connector F-20 (terminal No.2) 
and the ground.

NO [outside transmitter antenna assembly (trunk lid) 
connector F-20 terminal No.3 

− ground.] : Repair the 

wiring harness between outside transmitter antenna 
assembly (trunk lid) connector F-20 (terminal No.3) 
and the ground.

AC709707II

Harness side: F-20

AC709707IJ

Harness side: F-20

AC709707IK

Harness side: F-20

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-89

STEP 4. Keyless operation system communication test
Check that the communication with the outside transmitter 
antenna assembly (trunk lid) is normal (Refer to Antenna Test 

P.42B-275

).

Antennas to be checked
Trunk Lid antenna (exterior)

OK: Normal is displayed.

Q: Is the check result normal?

YES : Go to Step 5.
NO :  Replace the outside transmitter antenna assembly 

(trunk lid).

STEP 5. Check whether the diagnostic trouble code is 
reset.
(1) Erase the DTC.
(2) Turn the ignition switch from the LOCK (OFF) position to the 

ON position.

(3) Check if the DTC is set.
Q: Is the DTC set?

YES : Replace KOS-ECU and register the ID codes (Refer 

to 

P.42B-12

).

NO :  The procedure is complete.

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-90

DTC B240D: Front antenna(indoor) open

CAUTION

When replacing the ECU, always check that the 
communication circuit is normal.

.

DTC SET CONDITION

If an open circuit is detected in the inside transmitter 
antenna (front), the DTC is set.

.

TECHNICAL DESCRIPTION (COMMENT)

When the ignition push switch is pressed, or when 
the antenna open circuit detection request is 
received from the diagnosis function, the failure is 
detected.

AC609424

KOS-ECU

KEYLESS 
OPERATION 
KEY

SKY  BLUE

SKY  BLUE

SKY  BLUE

RED- BLA

CK

RED- BLA

CK

RED- BLA

CK

BLUE

BLUE

 Inside Transmission Antenna assembly (Front) Circuit

AC

INSIDE TRANSMISSION 

ANTENNA ASSEMBLY 

(FRONT)

AC708950AZ

Connector: C-05

AC708951BA

C-121

C-23

Connectors: C-23, C-121