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DTC U0155: Meter CAN timeout
 
 
cautionIf DTC U0155 is 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
The A/C control panel receives the air conditioning control-related signals from the combination meter via the CAN bus lines. If any of the air conditioning control-related signals from the combination meter cannot be received, diagnostic trouble code U0155 is set.
 
 
TECHNICAL DESCRIPTION (COMMENT)
Current trouble
  • Connector(s) or wiring harness in the CAN bus lines between the combination meter and the A/C control panel, the power supply system to the combination meter, the combination meter itself, or the A/C control panel may be defective.
Past trouble
  • If DTC U0155 is stored as a past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) in the CAN bus line between the A/C control panel and the combination meter, and the power supply system to the combination meter. If the connectors and wiring are normal, and obviously the ECU is the cause of the trouble, replace the ECU. If in doubt, do not replace the ECU.
    noteFor a past trouble, you cannot find it by the scan tool CAN bus diagnostics even if there is a failure in CAN bus lines. In this case, refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ) and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the DTC, which is set regarding the CAN communication-linked ECUs (Refer to GROUP 54C, Explanation about the scan too CAN bus diagnostics ).
 
 
TROUBLESHOOTING HINTS
  • Malfunction of the combination meter
  • Malfunction of the A/C control panel
  • Damaged wiring harness or connectors
 
 
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. Using scan tool MB991958 read the combination meter diagnostic trouble code.
Check whether a combination meter DTCs are set or not.
(1) Turn the ignition switch to the "ON" position.
(2) Check for combination meter DTC.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Diagnose the combination meter (Refer to GROUP 54A, Diagnostic Trouble Code ).
Go to Step 3.
 
STEP 3. Using scan tool MB991958, check for any diagnostic trouble code.
Check if a DTC, which relates to CAN communication-linked systems below, is set.
  • ETACS-ECU
    DTC indicating a time-out error related to the combination meter system
(1) Turn the ignition switch to the "ON" position.
(2) Check for a DTC related to the relevant system.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Go to Step 4.
Go to Step 5.
 
STEP 4. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the DTC set?
Replace the combination meter. 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 .)
 
STEP 5. Recheck for diagnostic trouble code.
Check again if the DTC is set.
(1) Turn the ignition switch to the "ON" position.
(2) Check if the DTC is set.
(3) 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 .)