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DTC U0019: Bus error (CAN-B)
 
 
cautionIf DTC U0019is set in the A/C control panel, diagnose the CAN main bus line.
cautionWhenever the ECU is replaced, ensure that the communication circuit is normal.
 
 
 
 
TROUBLE JUDGMENT
DTC U0019 will be set when the A/C control panel ceases CAN communication (bus off) and then resumes the communication when the ignition switch is turned to the "LOCK" (OFF) position.
 
 
TECHNICAL DESCRIPTION (COMMENT)
The wiring harness wire or connectors may have loose, corroded, or damage terminals, or terminals pushed back in the connector, or the A/C control panel may be defective.
 
 
TROUBLESHOOTING HINTS
  • Damaged wiring harness or connectors
  • Malfunction of the A/C control panel
 
 
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.
(1) Connect scan tool MB991958 to the data link connector
(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.
Is the DTC set?
Replace the A/C control panel. On completion, check that the DTC is not set again.
There is an intermittent malfunction such as poor engaged connector(s) or open circuit (Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .)