DTC B1731: ECM authentication timeout: Diagnosis

STEP 1. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if the DTC is set in ETACS-ECU.

CAUTION: To prevent damage to scan tool (M.U.T.-IIISE), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-IIISE).
1. Connect scan tool (M.U.T.-IIISE). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) ."
2. Erase the DTC.
3. 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.
4. On completion, check that the DTC is not set again.
Q: Is the DTC set?

YES: Go to Step 2.

NO: There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
STEP 2. Using scan tool (M.U.T.-IIISE), diagnose the CAN bus line.
1. Connect scan tool (M.U.T.-IIISE). Refer to "HOW TO CONNECT THE SCAN TOOL (M.U.T.-IIISE) ."
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 3.

NO: Repair the CAN bus line (Refer to DIAGNOSIS <CAN> ). On completion, go to Step 3.
STEP 3. Using scan tool (M.U.T.-IIISE), read the other system DTC.
Check whether an engine-related DTCs is set.

Q: Is the DTC set?

YES: Perform troubleshooting for the ECM (Refer to TROUBLESHOOTING ).

NO: Go to Step 4.
STEP 4. Using scan tool (M.U.T.-IIISE), read the other system DTC.
Check if DTC U0100 is set in ETACS-ECU.

Q: Is the DTC set?

YES: Go to Step 6.

NO: Go to Step 5.
STEP 5. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if the DTC is set in the ETACS-ECU.
1. 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.
2. Check if the DTC is set.
Q: Is the DTC set?

YES: Replace ETACS-ECU (Refer to ETACS-ECU ) and register the ID codes (Refer to ON-VEHICLE SERVICE ).

NO: Intermittent malfunction is suspected (Refer to HOW TO COPE WITH INTERMITTENT MALFUNCTIONS ).
STEP 6. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if the DTC is set in the ETACS-ECU.
1. 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.
2. Check if the DTC is set.
Q: Is the DTC set?

YES: Replace the engine control module and register the chassis number and key codes (Refer to HOW TO PERFORM VIN (CHASSIS NO.) WRITING ).

NO: The diagnosis is complete.