[Previous][Next]
DTC U0001: Bus-off error
 
 
caution
  • If there is any problem in the CAN bus lines, an incorrect DTC may be stored. Prior to this diagnosis, always diagnose the CAN bus lines.
  • Before replacing the ECU, ensure that the communication circuit is normal.
 
 
OPERATION
AWD-ECU monitors the CAN C-bus off interruption, and if any abnormality occurs, it interrupts the system.
 
 
DTC SET CONDITIONS
If the following conditions are met when the system is in operation (always), AWD-ECU gradually switches the control from AWD to FWD, flashes the AWD/LOCK indicators alternately, and stores DTC U0001.
  • IG1 voltage: 10 V or more
  • When CAN C-bus off interruption is detected
 
 
TROUBLESHOOTING HINTS
Current trouble
  • Wiring harness or connector failure of CAN bus line
  • AWD-ECU malfunction
Past trouble
  • Intermittent wiring harness or connector failure
    noteFor diagnosis procedures, refer to "How to treat past trouble" (Refer to GROUP 00 - How to Use Troubleshooting/How to Treat Past Trouble ).
 
 
DIAGNOSIS
STEP 1. Scan tool MB991958 CAN bus diagnostics
Use scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus line (Refer to GROUP 54C - Troubleshooting/CAN Bus Diagnostics Table ). Then go to Step 3.
 
STEP 2. Check whether the DTC is stored again.
(1) Erase the DTC.
(2) Turn the ignition switch from the LOCK (OFF) position to the ON position.
(3) Check if the DTC is stored.
Is DTC U0001 stored?
Replace AWD-ECU (Refer to ). Then go to Step 3 .
The trouble can be an intermittent malfunction such as loose connector fit, wiring harness open circuit (Refer to GROUP 00 - How to Use Troubleshooting/How to Cope with Intermittent Malfunctions ).
 
STEP 3. Check whether the DTC is stored again.
Is DTC U0001 stored?
Diagnose again from Step 1.
This diagnosis is complete.