If the diagnosis code No. B2101 or B2102 is set in KOS-ECU, always diagnose the CAN bus
lines.
Before replacing the ECU, ensure that the communication circuit is normal.
TROUBLE JUDGMENT
If the actual ignition switch status is different from the ignition switch status information
received from ETACS-ECU via CAN, KOS-ECU sets the diagnosis code No. B2101 or B2102.
JUDGEMENT CRITERIA
If the difference in the ignition switch level shown below occurs consecutively 10 times
with the ignition switch being the ON position or START position, when the CAN message (ignition
switch position information) from ETACS-ECU, KOS-ECU determines that there is a problem. B2101
Status of ignition switch: ON position
Ignition switch position information: OFF
B2102
Status of ignition switch: OFF position
Ignition switch position information: ON
PROBABLE CAUSES
Malfunction of CAN bus line
Malfunction of the KOS-ECU
Malfunction of the ignition switch
Damaged wiring harness and connectors
Malfunction of ETACS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use M.U.T.-III to diagnose the CAN bus lines.
Q.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C -
Troubleshooting ).
On completion, go to Step 2.
STEP 3. Check the wiring harness between the C-317 ETACS-ECU connector
terminal No. 5 and the C-104 KOS-ECU connector terminal No. 39.
Check the power supply line for open circuit.
Q.
Is the check result normal?
Go to Step 4.
Repair the wiring harness.
STEP 4. M.U.T.-III other system data list
Use M.U.T.-III to check the ETACS service data. (Refer to GROUP 54A -
ETACS,
Service Data Reference List ).
Item 254: IG voltage
OK: Battery voltage
Q.
Is the check result normal?
Go to Step 5.
Perform troubleshooting for ETACS (Refer to GROUP 54A -
ETACS -
Troubleshooting ).
STEP 5. Check whether the diagnosis code is reset.
(1)Erase the diagnosis code.
(2)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3)Check if the diagnosis code is set.
Q.
Is the diagnosis code set?
Replace KOS-ECU and register the ID codes (Refer to ).
Intermittent malfunction is suspected (Refer to GROUP 00 -
How to Use
Troubleshooting/Inspection Service Points -
How to Deal with Intermittent
Malfunction ).
)
)
)
)
)
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C -
Troubleshooting 
).
On completion, go to Step 2.