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| caution | If diagnostic trouble code No.U1109 is set in the auto A/C controller assembly (A/C-ECU), diagnose the CAN main bus line. |
| caution | Whenever the ECU is replaced, ensure that the communication circuit is normal. |
).| note | For a past trouble, you cannot 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 set regarding the CAN communication-linked ECUs (Refer to GROUP 54C - CAN Bus Line Diagnostic Flow ). |
| caution | If the ignition switch is turned "ON" without starting the engine and then three minutes pass, the A/C-ECU may set U1109 as past trouble. |
Go to Step 2.
Repair the CAN bus lines (Refer to GROUP 54C, Troubleshooting ). On completion, go to Step 6.Diagnose the ETACS-ECU (Refer to GROUP 54A, Troubleshooting ).Go to Step 3.Go to Step 4.Go to Step 5.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 ).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 ).Return to Step 1.The procedure is complete.