When the diagnosis
code No. B1A28 is set, be sure to diagnose the CAN bus line.
When replacing the ECU, always check that the communication circuit is normal.
DIAGNOSIS FUNCTION
ETACS-ECU sets diagnosis code No. B1A28 when the ETACS-ECU’s key certification
result and the engine-ECU’s starting condition do not match.
JUDGEMENT CRITERIA
ETACS-ECU determines that the abnormality is present, if the key certification result
OK but engine-ECU prohibits engine start by immobilizer function or key certification result
NG but engine permits engine starts.
PROBABLE CAUSES
Malfunction of CAN bus line
Malfunction of ETACS-ECU
Engine-ECU malfunction
Chassis number registered in engine-ECU unmatched
DIAGNOSIS PROCEDURE
STEP 1. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set to ETACS-ECU.
(1)Erase the diagnosis code.
(2)Remove the ignition key from key cylinder and insert it again then turn the ignition
switch from the Lock (OFF) position to the ON position.
(3)On completion, check that the diagnosis code is not reset.
Q.
Is the diagnosis code set?
Go to Step 2.
There is an intermittent malfunction such as poor engaged connector(s) or open
circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction ).
STEP 2. 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 3.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ).
STEP 3. M.U.T.-III other system diagnosis code
Check whether an engine-related diagnosis code is set.
Q.
Is the diagnosis code set?
Perform troubleshooting for the engine (Refer to GROUP 13A - Troubleshooting ).
Go to Step 4.
STEP 4. Diagnosis code check
Q.
Is diagnosis code No. B1761 or B2206 set?
Proceed to diagnosis code No. B1761 ( Chassis No. not programmed) or diagnosis code
No. B2206 (Chassis No. mismatch) (Refer to <B1761>, <B2206>).
Go to Step 5.
STEP 5. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Register the ignition key which is used when detect the diagnosis code.
(2)Remove the ignition key from the cylinder and then insert the ignition key again.
(3)After 2 or 3 seconds later from inserting the key, then turn the ignition ON.
(4)Check if the diagnosis code is set?
Q.
Is the diagnosis code set?
Go to Step 6.
The diagnosis is complete.
STEP 6. Check of chassis number registered in the ETACS-ECU and matching
check of vehicle’s chassis number.
Check if chassis number registered in the ETACS-ECU matches with the vehicle’s
chassis number.
(1)On the M.U.T.-III system selection screen, select "MPI/GDI/Diesel."
(2)Select "Coding."
(3)Select "Chassis No. Information."
(4)Compare it with the chassis number of the vehicle.
Q.
Do the chassis number registered in the ETACS-ECU and the vehicle’s chassis
number match?
Replace ETACS-ECU and register the ID codes (Refer to ).
Then go to Step 7.
Write the chassis number to the ETACS-ECU. [Refer to GROUP 00 - How
to Perform Chassis Number (Chassis No.) Writing ].
Record chassis number and go to Step 7.
STEP 7. Check whether the diagnosis code is reset.
Recheck if the diagnosis code is set.
(1)Register the ignition key which is used when detect the diagnosis code.
(2)Remove the ignition key from the cylinder and then insert the ignition key again.
(3)After 2 or 3 seconds later from inserting the key, then turn the ignition ON.
(4)Check if the diagnosis code is set?
Q.
Is the diagnosis code set?
Replace the engine-ECU and register the chassis number and key codes [Refer
to GROUP 00 - How to Perform Chassis Number (Chassis No.) Writing ].
There is an intermittent malfunction such as poor engaged connector(s) or open
circuit (Refer to GROUP 00, How to Cope with Intermittent Malfunction 
).