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DTC U0019: Bus off (CAN-B)
 
 
caution
  • If DTC U0019 is set, be sure to diagnose the CAN bus line.
  • When replacing the ECU, always check that the communication circuit is normal.
 
 
DIAGNOSTIC FUNCTION
If the CAN-B circuit malfunction occurs, the combination meter sets DTC U0019.
 
 
JUDGMENT CRITERIA
With the ignition switch at the ON position and the system voltage at 10 - 16 volts (data from ETACS-ECU), if the combination meter becomes unable to transmit data normally due to the CAN-B bus circuit malfunction, the combination meter determines that a problem has occurred.
 
 
TROUBLESHOOTING HINTS
  • The CAN bus line may be defective
  • The combination meter may be defective
  • The wiring harness or connectors may have loose, corroded, or damaged terminals, or terminals pushed back in the connector
 
 
DIAGNOSIS
STEP 1. Using scan tool MB991958, diagnose the CAN bus line.
(1)
cautionTo prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
Connect scan tool MB991958. Refer to "How to connect the Scan Tool (M.U.T.-III) ."
(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 2.
Repair the CAN bus line (Refer to GROUP 54C, Diagnosis ).
 
STEP 2. Recheck for diagnostic trouble code.
Check again if the DTC is set to the combination meter.
(1) Turn the ignition switch from "LOCK" (OFF) position to "ON" position.
(2) Check if DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Replace the combination meter.
The trouble can be an intermittent malfunction (Refer to GROUP 00 - How to use Troubleshooting/inspection Service Points - How to Cope with Intermittent Malfunction ).