Code No. B1731 ENG ECU authentification timeout
caution |
- When 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.
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DIAGNOSTIC FUNCTION
If the necessary data cannot be received from engine-ECU via CAN bus line during the engine starting certification with engine-ECU, KOS&OSS-ECU determines that a problem has occurred, and sets diagnosis code No.B1731. At the same time, KOS&OSS-ECU displays the immobilizer certification system inspection warning to the combination meter.
JUDGEMENT CRITERIA
Check Conditions
- At engine starting certification
Judgement Criterion
- At the engine starting certification with engine-ECU, necessary data cannot be received from engine-ECU via CAN bus line.
PROBABLE CAUSES
- Malfunction of the CAN bus line
- Malfunction of engine-ECU
- Malfunction of KOS&OSS-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III CAN bus diagnostics
Use the 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
).
STEP 2. M.U.T.-III other system diagnosis code
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(1)Check that the vehicle power can be turned ON and engine is started.
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(2)Check the diagnosis code of engine-ECU.
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Q.
Is the diagnosis code set?
Troubleshoot the engine-ECU (Refer to GROUP 13B - Troubleshooting
<6B3> or GROUP 13C - Troubleshooting
<4N1>). Then go to Step 3.
Go to Step 3.
STEP 3. Check whether the diagnosis code is set again.
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(1)Operate the engine switch several times within five seconds without depressing the brake pedal to turn on and off the power supply mode.
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(2)Check again if the diagnosis code is set in the KOS&OSS-ECU.
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Q.
Is the diagnosis code set?
Replace the KOS&OSS-ECU and register the chassis number (Refer to
). Then go to Step 4.
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction
).
STEP 4. Check whether the diagnosis code is set again.
Check again if the diagnosis code is set in the KOS&OSS-ECU.
Q.
Is the diagnosis code set?
Replace the engine-ECU (Refer to GROUP 13B - Engine-ECU
<6B3> or GROUP 13C - Engine-ECU
<4N1>).
Intermittent malfunction is suspected (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunction
).