Mitsubishi Evolution X. Manual - part 530

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-27

DTC B1A10: Keyless/KOS key 1 low battery

 

DTC B1A11: Keyless/KOS key 2 low battery

 

DTC B1A12: Keyless/KOS key 3 low battery

 

DTC B1A13: Keyless/KOS key 4 low battery

CAUTION

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

.

DIAGNOSTIC FUNCTION

If KOS-ECU receives the keyless operation key low 
battery voltage signal, KOS-ECU sets the DTC  No. 
B1A10, B1A11, B1A12, or B1A13.

.

JUDGEMENT CRITERIA

• B1A10: If KOS-ECU receives the keyless opera-

tion key 1 (the first keyless operation key regis-
tered with KOS-ECU) low battery voltage signal 
in five consecutive times, it is judged as abnor-
mal.

• B1A11: If KOS-ECU receives the keyless opera-

tion key 2 (the second keyless operation key reg-
istered with KOS-ECU) low battery voltage signal 
in five consecutive times, it is judged as abnor-
mal.

• B1A12: If KOS-ECU receives the keyless opera-

tion key 3 (the third keyless operation key regis-
tered with KOS-ECU) low battery voltage signal 
in five consecutive times, it is judged as abnor-
mal.

• B1A13: If KOS-ECU receives the keyless opera-

tion key 4 (the fourth keyless operation key regis-
tered with KOS-ECU) low battery voltage signal 
in five consecutive times, it is judged as abnor-
mal.

.

PROBABLE CAUSES

• Malfunction of the keyless operation key battery

• Malfunction of the keyless operation key

• Malfunction of KOS-ECU

DIAGNOSTIC PROCEDURE

STEP 1. Replace the battery in the keyless 
operation key and recheck the diagnostic trouble 
code.
Replace the battery of the keyless operation key for 
which the DTC is set, and check whether the DTC is 
reset.
(1) Replace the battery of the keyless operation key 

for which the DTC is set.

(2) Erase the DTC.
(3) Turn the ignition switch from the LOCK (OFF) 

position to the ON position.

(4) Lock or unlock the keyless operation key.
(5) Check if the DTC is set.

Q: Is the DTC set?

YES : 

Go to Step 2.

NO : 

The diagnosis is complete (Discharged 
battery).

STEP 2. Replace the keyless operation key and 
recheck the diagnostic trouble code.
Replace the keyless operation key for which the DTC 
is set with a new one, register the key ID and keyless 
operation key ID (refer to 

P.42B-265

), and check 

whether the DTC 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 diagnosis is complete.

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-28

DTC B1A24: Key ID not registered

CAUTION

• When the DTC B1A24 is set, be sure to diag-

nose the CAN bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DTC SET CONDITION

KOS-ECU sets DTC B1A24 when the key ID was not 
registered in it. 

.

TECHNICAL DESCRIPTION (COMMENT)

KOS-ECU determines that the abnormality is 
present, if the key ID is not registered in it when the 
ignition switch is turned ON.

.

TROUBLESHOOTING HINTS

• Key ID not registered

• Malfunction of the keyless operation key

• Malfunction of KOS-ECU

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicles Communication Interface (V.C.I.)

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line.

CAUTION

To prevent damage to scan tool (MB991958), always turn 
the ignition switch to the "LOCK" (OFF) position before 
connecting or disconnecting scan tool (MB991958).
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis 

P.54C-14

).

AC608435

Data link connector

MB991827

MB991824

MB991910

AB

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-29

STEP 2. Register the key ID and recheck the diagnostic 
trouble code.
Register the key ID and keyless operation key ID of the keyless 
operation key by which the DTC is set (refer to 

P.42B-12

), and 

recheck if the DTC is set.
(1) Turn the ignition switch from the "LOCK" (OFF) position to 

the "ON" position.

(2) 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.

DTC B1A25: Key ID unmatched

CAUTION

• When the DTC B1A25 is set, be sure to diag-

nose the CAN bus line.

• When replacing the ECU, always check that 

the communication circuit is normal.

.

DTC SET CONDITION

KOS-ECU sets DTC B1A25 when the received key 
ID is different from the one registered in it. 

.

TECHNICAL DESCRIPTION (COMMENT)

KOS-ECU determines that the abnormality is 
present, if the key ID does not match the one regis-
tered in it when the ignition switch is turned ON.

.

TROUBLESHOOTING HINTS

• Malfunction of the keyless operation key

• Accessory key not registered

• Accessory KOS-ECU not registered

• Key is registered to another vehicle

• Malfunction of KOS-ECU

DIAGNOSIS

Required Special Tools:

• MB991958: Scan Tool (M.U.T.-III Sub Assembly)

• MB991824: Vehicles Communication Interface (V.C.I.)

• MB991827: M.U.T.-III USB Cable

• MB991910: M.U.T.-III Main Harness A

DIAGNOSIS

TSB Revision

KEYLESS OPERATION SYSTEM (KOS)

42B-30

STEP 1. Using scan tool MB991958, diagnose the CAN bus 
line.

CAUTION

To prevent damage to scan tool (MB991958), always turn 
the ignition switch to the "LOCK" (OFF) position before 
connecting or disconnecting scan tool (MB991958).
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Diagnose the CAN bus line.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the CAN bus line found to be normal?

YES : Go to Step 2.
NO :  Repair the CAN bus line (Refer to GROUP 54C, 

Diagnosis 

P.54C-14

).

STEP 2. Register the key ID and recheck the diagnostic 
trouble code.
Register the key ID and keyless operation key ID of the keyless 
operation key by which the DTC is set (refer to 

P.42B-12

), and 

recheck if the DTC is set.
(1) Turn the ignition switch from the "LOCK" (OFF) position to 

the "ON" position.

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

YES : Go to Step 3.
NO :  The procedure is complete.

STEP 3. Replace the keyless operation key and recheck 
the diagnostic trouble code.
Replace the keyless operation key for which the DTC is set 
with the other key,  and check whether the DTC is reset.
(1) Turn the ignition switch from the "LOCK" (OFF) position to 

the "ON" position.

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

YES : Go to Step 4.
NO :  Go to Step 5.

AC608435

Data link connector

MB991827

MB991824

MB991910

AB