U1002

CAN COMMUNICATION: CAN COMMUNICATION SYSTEM: U1002 (CAN MS BUS): Lost Communication with Gateway Module (Main body ECU)

DTC U1002 (CAN MS BUS) - Lost Communication with Gateway Module (Main body ECU)

DESCRIPTION

- The main body ECU will store this DTC when no signals can be received from the ECUs that have been memorized as those that are connected to the CAN MS bus.
- When the main body ECU receives a response signal from the ECUs connected to the CAN MS bus, the main body ECU recognizes and memorizes that the ECU is connected to the CAN MS bus. Based on this memorized data, the main body ECU monitors for malfunctions in the ECUs connected to the CAN MS bus when communicating with those ECUs. If the main body ECU cannot receive response signals from the ECUs that have been memorized as those connected to the CAN MS bus, the main body ECU determines that a malfunction exists.

WIRING DIAGRAM

INSPECTION PROCEDURE
NOTICE:
- Turn the ignition switch off before measuring the resistances of CAN bus main wires and CAN bus branch wires.
- After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not in operation.
- Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches, or the doors. If any doors need to be opened in order to check connectors, open the doors and leave them open.
HINT:
- Operating the ignition switch, any other switches, or a door triggers related ECU and sensor communication on the CAN. This communication will cause the resistance value to change.
- Even after DTCs are cleared, if a DTC is stored again after driving the vehicle for a while, the malfunction may be occurring due to vibration of the vehicle. In such a case, wiggling the ECUs or wire harness while performing the inspection below will help determine the cause of the malfunction.

PROCEDURE

1. CHECK VEHICLE TYPE
Result:

B -- CHECK CAN MS BUS WIRE
A -- Continue to next step.
2. CHECK CAN MS BUS WIRE
(a) Turn the ignition switch off.
(b) Disconnect the certification ECU connector.

Result:

C -- CHECK FOR SHORT IN CAN MS BUS WIRES
B -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
A -- Continue to next step.
3. CHECK CAN MS BUS WIRE
(a) Reconnect the certification ECU connector.
(b) Disconnect the main body ECU connector.

NG -- REPLACE CERTIFICATION ECU
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
4. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
(a) Reconnect the certification ECU connector.
(b) Disconnect the main body ECU connector.

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU - CERTIFICATION ECU)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
5. CHECK FOR SHORT IN CAN MS BUS WIRES
(a) Disconnect the main body ECU connector (D9).

(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU - CERTIFICATION ECU)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
6. CHECK CAN MS BUS WIRE
(a) Turn the ignition switch off.

(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

Result:

C -- CHECK FOR SHORT IN CAN MS BUS WIRES
B -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
A -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
7. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE

(a) Disconnect the main body ECU junction connector from the CAN junction connector RR.

(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

Result:

C -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
B -- REPLACE CAN JUNCTION CONNECTOR RR
A -- Continue to next step.
8. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
(a) Reconnect the main body ECU junction connector to the CAN junction connector RR.
(b) Disconnect the main body ECU connector (D9) from the main body ECU.

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU MAIN WIRE)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
9. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE
(a) Reconnect the main body ECU junction connector to the CAN junction connector RR.
(b) Disconnect the certification ECU connector from the certification ECU.

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CERTIFICATION ECU BRANCH WIRE)
OK -- REPLACE CERTIFICATION ECU
10. CHECK FOR SHORT IN CAN MS BUS WIRES
(a) Disconnect the back door ECU connector.

(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

NG -- CHECK FOR SHORT IN CAN MS BUS WIRES
OK -- REPLACE BACK DOOR MOTOR UNIT (BACK DOOR ECU)
11. CHECK FOR SHORT IN CAN MS BUS WIRES

(a) Disconnect the back door ECU junction connector from the CAN junction connector RR.

(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:

NG -- REPAIR OR REPLACE CAN MS BUS BRANCH WIRE OR CONNECTOR (BACK DOOR ECU)
OK -- Continue to next step.
12. CHECK FOR SHORT IN CAN MS BUS WIRES
(a) Reconnect the back door ECU junction connector to the CAN junction connector RR.

(b) Disconnect the main body ECU junction connector from the CAN junction connector RR.

Result:

C -- CHECK FOR SHORT IN CAN MS BUS WIRES
B -- REPLACE CAN JUNCTION CONNECTOR RR
A -- Continue to next step.
13. CHECK FOR SHORT IN CAN BUS MAIN WIRE
(a) Reconnect the main body ECU junction connector to the CAN junction connector RR.
(b) Disconnect the main body ECU connector (D9) from the main body ECU.

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU MAIN WIRE)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
14. CHECK FOR SHORT IN CAN MS BUS WIRES
(a) Reconnect the main body ECU junction connector to the CAN junction connector RR.

(b) Disconnect the certification ECU junction connector from the CAN junction connector RR.

NG -- REPLACE CAN JUNCTION CONNECTOR RR
OK -- Continue to next step.
15. CHECK FOR SHORT IN CAN MS BUS WIRES
(a) Reconnect the certification ECU junction connector to the CAN junction connector RR.
(b) Disconnect the certification ECU connector from the certification ECU.

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CERTIFICATION ECU BRANCH WIRE)
OK -- REPLACE CERTIFICATION ECU