[Previous][Next]
DTC B1731 ECM authentication timeout
 
 
caution
  • When DTC B1731 is set, be sure to diagnose the CAN bus line.
  • When replacing the ECU, always check that the communication circuit is normal.
 
 
DIAGNOSTIC FUNCTION
ETACS-ECU checks if the data from the engine control module is received via the CAN bus line. When ETACS-ECU cannot receive the engine control module data, it sets DTC B1731.
 
 
TROUBLE JUDGMENT
ETACS-ECU determines that the abnormality is present, if it cannot receive the data from the engine control module via the CAN bus line when the ignition switch is turned "ON".
 
 
TROUBLESHOOTING HINTS
  • The CAN bus line may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connectors
  • The Engine control module may be defective
  • The ETACS-ECU may be defective
 
 
DIAGNOSIS
STEP 1. Using scan tool (M.U.T.-IIISE), read the DTC again.
Check again if the DTC is set in ETACS-ECU.
(1)
cautionTo 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).
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.
Is the DTC 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. 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.
Is the CAN bus line found to be normal?
Go to Step 3.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting ). 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.
Is the DTC set?
Perform troubleshooting for the ECM (Refer to GROUP 13A - Troubleshooting ).
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.
Is the DTC set?
Go to Step 6.
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.
Is the DTC set?
Replace ETACS-ECU (Refer to ) and register the ID codes (Refer to ).
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction ).
 
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.
Is the DTC set?
Replace the engine control module and register the chassis number and key codes [Refer to GROUP 00 - How to Perform VIN (Chassis No.) Writing ].
The diagnosis is complete.