Technical Description (Comment)

The scan tool MB991958 shows a DTC status as active. 

• Connector(s) or wiring harness in the CAN bus lines between the combination meter and the ETACS-ECU, the power supply circuits to the ETACS-ECU itself may be defective.

The scan tool MB991958 shows a DTC status as stored. 

• If DTC U1109 is set as past trouble, carry out diagnosis with particular emphasis on wiring and connector(s) in the CAN bus lines between the combination meter and the ETACS-ECU, or power supply to the ETACS-ECU. For diagnostic procedures, refer to HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO TREAT PAST TROUBLE .
  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 HOW TO USE TROUBLESHOOTING/INSPECTION SERVICE POINTS - HOW TO COPE WITH INTERMITTENT MALFUNCTIONS and check the CAN bus lines. You can narrow down the probable cause of the trouble by referring to the DIAGNOSTIC TROUBLE CODE , which is set regarding the CAN communication-linked ECUs (Refer to CAN BUS LINE DIAGNOSTIC FLOW .