Mitsubishi Evolution X. Manual - part 541

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-71

STEP 5. Replace the key reminder switch, and 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 trouble can be an intermittent malfunction (Refer 

to GROUP 00 

− How to use 

Troubleshooting/inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-17

).

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-72

DTC B240A: FR antenna(outdoor) open

CAUTION

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

AC609050

KOS-ECU

KEYLESS 
OPERATION 
KEY

OUTSIDE TRANSMISSION 
ANTENNA ASSEMBLY 
(DRIVER'S SIDE)

SKY  BLUE

SKY  BLUE

SKY  BLUE

RED- BLA

CK

RED- BLA

CK

RED- BLA

CK

 Outside Transmission Antenna assembly (Driver's Side) Circuit

AC

RED- YELLO

W

RED-YELLO

W

AC708950AZ

Connector: C-05

AC708951AZ

Connector: C-23

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-73

.

DTC SET CONDITION

If an open circuit is detected in the outside transmit-
ter antenna (driver's side), 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.

.

TROUBLESHOOTING HINTS

• Malfunction of the outside transmitter antenna 

assembly (driver's side)

• Malfunction of the KOS-ECU

• Damaged wiring harness and connectors

DIAGNOSIS

STEP 1. Check KOS-ECU connector C-05 and outside 
transmitter antenna assembly (driver's side) connector 
D-23 for loose, corroded or damaged terminals, or 
terminals pushed back in the connector.
Q: Are KOS-ECU connector C-05 and outside transmitter 

antenna assembly (driver's side) connector D-23 in 
good condition?
YES : Go to Step 2.
NO :  Repair or replace the damaged component(s). Refer 

to GROUP 00E, Harness Connector Inspection 

P.00E-2

. Check that the outside transmitter antenna 

assembly (driver's side) works normally.

AC708955AP

Connector: D-23

DIAGNOSIS

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KEYLESS OPERATION SYSTEM (KOS)

42B-74

STEP 2. Check the wiring harness between the KOS-ECU 
connector C-05 (terminal Nos. 6, 17, 40) and outside 
transmitter antenna assembly (driver's side) connector 
D-23 (terminal Nos. 3, 2, 1) for open circuit.
(1) Disconnect KOS-ECU connector C-05 and outside 

transmitter antenna assembly (driver's side) connector 
D-23, and check the wiring harness.

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

C-05 (terminal No.6) and outside transmitter antenna 
assembly (driver's side) connector D-23 (terminal No.3).

OK: Continuity exists (2 

Ω or less)

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

C-05 (terminal No.17) and outside transmitter antenna 
assembly (driver's side) connector D-23 (terminal No.2).

OK: Continuity exists (2 

Ω or less)

AC709707ET

Harness side: C-05

Harness side: D-23

AC709707EU

Harness side: C-05

Harness side: D-23