CAN Communication System

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: U1104: Lost Communication with Driving Support ECU

DTC U1104 - Lost Communication with Driving Support ECU

DESCRIPTION

If 2 or more DTCs are output during the DTC check, one side of the CAN branch wire may be open. (One side of the CANH [branch wire]/CANL [branch wire] of the ECU and/or sensor is open.)





HINT: For vehicles with dynamic radar control system or pre-collision system only.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. DISCONNECT CABLE FROM NEGATIVE BATTERY TERMINAL
(a) Disconnect the cable from the negative (-) battery terminal before measuring the resistances of the main wire and the branch wire.
CAUTION:
Wait at least 90 seconds after disconnecting the cable from the negative (-) battery terminal to prevent airbag and seat belt pretensioner activation.
NOTICE:
- After the engine switch is turned off, the HDD navigation system requires approximately 6 minutes to record various types of memory and settings. As a result, after turning the engine switch off, wait 6 minutes or more before disconnecting the cable from the negative (-) battery terminal.
- When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.

NEXT -- Continue to next step.

2. CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU BRANCH WIRE)




(a) Disconnect the A33 driving support ECU connector.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPAIR OR REPLACE DRIVING SUPPORT ECU BRANCH WIRE OR CONNECTOR (CA1P, CA1N)
OK -- Continue to next step.

3. CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU - BATTERY AND BODY GROUND)
(a) Connect the cable to the negative (-) battery terminal.
NOTE:
When disconnecting the cable, some systems need to be initialized after the cable is reconnected Repair Instruction - Initialization.




(b) Disconnect the A33 driving support ECU connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard resistance:





(d) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE DRIVING SUPPORT ECU