Multiport Fuel Injection (MFI)
DTC U0001: Bus OffCAUTION:
- If the ECM output the DTC U0001, make sure to diagnose the CAN bus line.
- Before replacing the ECU, make sure that the communication circuit is operating normally.
DTC SET CONDITIONS
Check Conditions
- Always
Judgement Criteria
- Bus off error detected
FAIL-SAFE AND BACKUP FUNCTION
- None
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- CAN line harness damage or connector damage.
- ECM failed.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
STEP 1. Using scan tool MB991958, diagnose CAN bus line.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Diagnose CAN bus line.
4. Turn the ignition switch the "LOCK" (OFF) position.
Q: Is the CAN bus line normal?
YES : Go to Step 2.
NO : Repair the CAN bus line. Then go to Step 3.
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if the DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC U0001 set?
YES : Replace the ECM. When the ECM is replaced, register the ID code. Then go to Step 3.
NO : It can be assumed that this malfunction is intermitten.
STEP 3. Recheck for diagnostic trouble code.
Check again if the DTC is set.
1. Erase the DTC.
2. Turn the ignition switch to the "ON" position.
3. Check if DTC is set.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC U0001 set?
YES : Replay the troubleshooting.
NO : The inspection is complete.