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Code No. U1109: ETACS-ECU CAN time-out/Not equipped
cautionIf diagnostic trouble code No.U1109 is stored in the auto A/C controller assembly (A/C-ECU), diagnose the CAN main bus line.
cautionWhenever the ECU is replaced, ensure that the communication circuit is normal.
 
 
 
 
TROUBLE JUDGMENT
The auto A/C controller assembly (A/C-ECU) receives air conditioning operation-related signal from the ETACS-ECU via the CAN bus lines. If the auto A/C controller assembly (A/C-ECU) cannot receive the air conditioning operation-related signal at all on the ETACS-ECU, diagnostic trouble code No.U1109 will be stored.
 
 
 
COMMENTS ON TROUBLE SYMPTOM
Current trouble
  • Connector(s) or wiring harness in the CAN bus lines between the ETACS-ECU and the auto A/C controller assembly (A/C-ECU), the power supply system to the ETACS-ECU, the ETACS-ECU itself, or the auto A/C controller assembly (A/C-ECU) may be faulty.
Past trouble
  • Carry out diagnosis with particular emphasis on connector(s) or wiring harness in the CAN bus lines between the ETACS-ECU and the auto A/C controller assembly (A/C-ECU), and the power supply system to the ETACS-ECU. For diagnosis procedures, refer to "How to treat past trouble" (Refer to GROUP 00 - How to Treat Past Trouble ).
    noteFor a past trouble, you can not find it by the scan tool MB991958 CAN bus diagnostics even if there is any failure in CAN bus lines. In this case, refer to GROUP 00, How to Cope with Intermittent Malfunction and check the CAN bus lines. You can narrow down the possible cause of the trouble by referring to the diagnostic trouble code, which is stored regarding the CAN communication-linked ECUs (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ).
    cautionIf the ignition switch is turned on without starting the engine and then three minutes pass, the A/C-ECU may store U1109 as past trouble.
 
 
 
PROBABLE CAUSES
  • Damaged wiring harness or connectors
  • Malfunction of the ETACS-ECU
  • Malfunction of the auto A/C controller assembly (A/C-ECU)
 
 
 
 
DIAGNOSIS
STEP 1. Using SCAN tool MB991958, diagnose the CAN bus lines.
Use the scan tool MB991958 to diagnose the CAN bus lines.
Is the check result normal?
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C, Troubleshooting ). On completion, go to Step 6.
 
STEP 2. Check whether the DTC is stored.
Check whether the ETACS-related diagnostic trouble code is stored.
Is the diagnostic trouble code stored?
Diagnose the ETACS-ECU. (Refer to GROUP 54A, Troubleshooting ).
Go to Step 3.
 
STEP 3. Check whether the DTC is stored again.
Check if a diagnostic trouble code, which relates to CAN communication-linked systems below, is stored.
  • ETACS-ECU
    U1109: ETACS-related time-out diagnostic trouble code
Is the diagnostic trouble code stored?
Go to Step 4.
Go to Step 5.
 
STEP 4. Check whether the diagnostic trouble code is stored again.
Recheck if the diagnostic trouble code is stored.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnostic trouble code is stored.
Is the diagnostic trouble code stored?
Replace the ETACS-ECU, and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus line between the ETACS-ECU and the auto A/C controller assembly (A/C-ECU) (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
 
STEP 5. Check whether the diagnostic trouble code is stored again.
Recheck if the diagnostic trouble code is stored.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnostic trouble code is stored.
Is the diagnostic trouble code stored?
Replace the auto A/C controller assembly (A/C-ECU), and then go to Step 6.
A poor connection, open circuit or other intermittent malfunction in the CAN bus line between the ETACS-ECU and the auto A/C controller assembly (A/C-ECU) (Refer to GROUP 00 - How to Cope with Intermittent Malfunction ).
 
STEP 6. Check whether the diagnostic trouble code is stored again.
Recheck if the diagnostic trouble code is stored.
(1) Erase the diagnostic trouble code.
(2) Ignition switch: LOCK (OFF) to ON
(3) Check if the diagnostic trouble code is stored.
Is the diagnostic trouble code stored?
Return to Step 1.
The procedure is complete.