Code No.B1731 Engine ECU authentification timeout


caution
  • When the diagnosis code No. B1731 is set, be sure to diagnose the CAN bus line.
  • When replacing the ECU, always check that the communication circuit is normal.

DIAGNOSIS FUNCTION



JUDGEMENT CRITERIA



PROBABLE CAUSES



  • Malfunction of CAN bus line
  • Damaged wiring harness and connectors
  • Malfunction of Engine-ECU
  • Malfunction of WCM
  • Malfunction of ETACS-ECU

DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III CAN bus diagnostics



Q. Is the check result normal?





STEP 2. M.U.T.-III other system diagnosis code



Q. Is the diagnosis code set?





STEP 3. M.U.T.-III other system diagnosis code



Q. Is the diagnosis code set?





STEP 4. Check whether the diagnosis code is reset.



(1)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?





STEP 5. Check whether the diagnosis code is reset.



(1)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?





STEP 6. Check whether the diagnosis code is reset.



(1)Turn the ignition switch from the LOCK (OFF) position to the ON position.
(2)Check if the diagnosis code is set.

Q. Is the diagnosis code set?