Mitsubishi Evolution X. Manual — part 546

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-91

.

TROUBLESHOOTING HINTS

• Malfunction of the inside transmitter antenna

assembly (front)

• Malfunction of the KOS-ECU

• Damaged wiring harness and connectors

DIAGNOSIS

STEP 1. Check KOS-ECU connector C-05 and inside
transmitter antenna assembly (front) connector C-121 for
loose, corroded or damaged terminals, or terminals
pushed back in the connector.
Q: Are KOS-ECU connector C-05 and inside transmitter

antenna assembly (front) connector C-121 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 inside transmitter antenna

assembly (front) works normally.

STEP 2. Check the wiring harness between the KOS-ECU
connector C-05 (terminal Nos. 6, 16, 40) and inside
transmitter antenna assembly (front) connector C-121
(terminal Nos. 3, 2, 1) for open circuit.
(1) Disconnect KOS-ECU connector C-05 and inside

transmitter antenna assembly (front) connector C-121, and
check the wiring harness.

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

C-05 (terminal No.6) and inside transmitter antenna
assembly (front) connector C-121 (terminal No.3).

OK: Continuity exists (2

Ω or less)

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

C-05 (terminal No.16) and inside transmitter antenna
assembly (front) connector C-121 (terminal No.2).

OK: Continuity exists (2

Ω or less)

AC709707FN

Harness side: C-05

Harness side: C-121

AC709707 FO

Harness side: C-05

Harness side: C-121

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-92

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

C-05 (terminal No.40) and inside transmitter antenna
assembly (front) connector C-121 (terminal No.1).

OK: Continuity exists (2

Ω or less)

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

(terminal Nos. 6, 16, 40) and inside transmitter antenna
assembly (front) connector C-121 (terminal Nos. 3, 2, 1)
in good condition?
YES : Go to Step 3.
NO (KOS-ECU connector C-05 terminal No.6

− inside

transmitter antenna assembly (front) connector C-121
terminal No.3.) : Repair the wiring harness between

KOS-ECU connector C-05 (terminal No.6) and inside
transmitter antenna assembly (front) connector C-121
(terminal No.3).

NO (KOS-ECU connector C-05 terminal No.16

− inside

transmitter antenna assembly (front) connector C-121
terminal No.2.) : Repair the wiring harness between

KOS-ECU connector C-05 (terminal No.16) and
inside transmitter antenna assembly (front) connector
C-121 (terminal No.2).

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

− inside

transmitter antenna assembly (front) connector C-121
terminal No.1.) : Repair the wiring harness between

KOS-ECU connector C-05 (terminal No.40) and
inside transmitter antenna assembly (front) connector
C-121 (terminal No.1).

AC709707

Harness side: C-121

Harness side: C-05

FP

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-93

STEP 3. Check the wiring harness between the inside
transmitter antenna assembly (front) connector C-121
(terminal Nos. 3, 2, 1) and the ground for short circuit.
(1) Disconnect inside transmitter antenna assembly (front)

connector C-121, and check the wiring harness.

(2) Check the wiring harness between inside transmitter

antenna assembly (front) connector C-121 (terminal No.3)
and ground

OK: No continuity

(3) Check the wiring harness between inside transmitter

antenna assembly (front) connector C-121 (terminal No.2)
and ground

OK: No continuity

(4) Check the wiring harness between inside transmitter

antenna assembly (front) connector C-121 (terminal No.1)
and ground

OK: No continuity

Q: Is the wiring harness between inside transmitter

antenna assembly (front) connector C-121 (terminal
Nos. 3, 2, 1) and the ground in good condition?
YES : Go to Step 4.
NO [inside transmitter antenna assembly (front)
connector C-121 terminal No.3

− ground.] : Repair the

wiring harness between inside transmitter antenna
assembly (front) connector C-121 (terminal No.3) and
ground.

NO [inside transmitter antenna assembly (front)
connector C-121 terminal No.2

− ground.] : Repair the

wiring harness between inside transmitter antenna
assembly (front) connector C-121 (terminal No.2) and
the ground.

NO [inside transmitter antenna assembly (front)
connector C-121 terminal No.1

− ground.] : Repair the

wiring harness between inside transmitter antenna
assembly (front) connector C-121 (terminal No.1) and
the ground.

AC709707IL

Harness side: C-121

AC709707IM

Harness side: C-121

AC709707IN

Harness side: C-121

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-94

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

P.42B-275

).

Antennas to be checked

• front antenna (interior)

OK: Normal is displayed.

Q: Is the check result normal?

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

(front).

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.