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 power switch off before measuring the resistances of the CAN bus main wires and CAN bus branch wires.
- After the power 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 power 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 power 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 CAN MS BUS WIRE
(a) Turn the power 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 (CAN JUNCTION CONNECTOR LH)
B -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN JUNCTION CONNECTOR LH)
A -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
2. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN JUNCTION CONNECTOR LH)
(a) Disconnect the CAN junction connector LH.

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

Result:

D -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN JUNCTION CONNECTOR RR)
C -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CERTIFICATION ECU)
B -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU)
A -- REPLACE JUNCTION CONNECTOR
3. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU)
(a) Reconnect the CAN junction connector LH.
(b) Disconnect the main body ECU connector (D9) from the main body ECU.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - MAIN BODY ECU MAIN WIRE)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
4. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CERTIFICATION ECU)
(a) Reconnect the CAN junction connector LH.
(b) Disconnect the certification ECU connector from the certification ECU.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - CERTIFICATION ECU MAIN WIRE)
OK -- REPLACE CERTIFICATION ECU
5. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN JUNCTION CONNECTOR RR)
(a) Reconnect the CAN junction connector LH.

(b) Disconnect the three connectors from the CAN junction connector RR.

(c) Measure the resistance according to the value(s) in the table below.
NOTE: Measure the resistance with the CAN junction connector LH connected.

Standard resistance:

Result:

C -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CERTIFICATION ECU)
B -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - CAN JUNCTION CONNECTOR RR)
A -- REPLACE CAN JUNCTION CONNECTOR RR
6. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CERTIFICATION ECU)
(a) Reconnect the CAN junction connector LH and CAN junction connector RR.
(b) Disconnect the certification ECU connector from the certification ECU.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR RR - CERTIFICATION ECU MAIN WIRE)
OK -- REPLACE CERTIFICATION ECU
7. CHECK FOR SHORT IN CAN MS BUS WIRES (CAN JUNCTION CONNECTOR LH)
(a) Disconnect the CAN junction connector LH.

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

Result:

E -- CHECK FOR SHORT IN CAN MS BUS WIRES (CAN JUNCTION CONNECTOR RR)
D -- CHECK FOR SHORT IN CAN BUS MAIN WIRE (TIRE PRESSURE WARNING ECU)
C -- CHECK FOR SHORT IN CAN MS BUS WIRES (CERTIFICATION ECU)
B -- CHECK FOR SHORT IN CAN MS BUS WIRES (MAIN BODY ECU)
A -- REPLACE CAN JUNCTION CONNECTOR LH
8. CHECK FOR SHORT IN CAN MS BUS WIRES (MAIN BODY ECU)
(a) Disconnect the main body ECU connector (D9) from the main body ECU.

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

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - MAIN BODY ECU MAIN WIRE)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY (MAIN BODY ECU)
9. CHECK FOR SHORT IN CAN MS BUS WIRES (CERTIFICATION ECU)
(a) Disconnect the certification ECU connector from the certification ECU.

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

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - CERTIFICATION ECU MAIN WIRE)
OK -- REPLACE CERTIFICATION ECU
10. CHECK FOR SHORT IN CAN BUS MAIN WIRE (TIRE PRESSURE WARNING ECU)
(a) Disconnect the tire pressure warning ECU connector from the tire pressure warning ECU.

(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 (CAN JUNCTION CONNECTOR RR - TIRE PRESSURE WARNING ECU)
OK -- REPLACE TIRE PRESSURE MONITOR ECU (TIRE PRESSURE WARNING ECU)
11. CHECK FOR SHORT IN CAN MS BUS WIRES (CAN JUNCTION CONNECTOR RR)

(a) Disconnect the three connectors from the CAN junction connector RR.

(b) Check the three connectors for short.
Standard resistance:

Result:

D -- CHECK FOR SHORT IN CAN MS BUS WIRES (BACK DOOR ECU)
C -- CHECK FOR SHORT IN CAN MS BUS WIRES (CERTIFICATION ECU)
B -- CHECK FOR SHORT IN CAN MS BUS WIRES (CAN JUNCTION CONNECTOR LH)
A -- REPLACE CAN JUNCTION CONNECTOR RR
12. CHECK FOR SHORT IN CAN MS BUS WIRES (CAN JUNCTION CONNECTOR LH)

(a) Measure the resistance according to the value(s) in the table below.
NOTE: Measure the resistance with the three connectors disconnected from the CAN junction connector RR.

Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR LH - CAN JUNCTION CONNECTOR RR)
OK -- REPLACE CAN JUNCTION CONNECTOR LH
13. CHECK FOR SHORT IN CAN MS BUS WIRES (CERTIFICATION ECU)
(a) Disconnect the certification ECU connector from the certification ECU.

(b) Measure the resistance according to the value(s) in the table below.
NOTE: Measure the resistance with the three connectors disconnected from the CAN junction connector RR.

Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR RR - CERTIFICATION ECU MAIN WIRE)
OK -- REPLACE CERTIFICATION ECU
14. CHECK FOR SHORT IN CAN MS BUS WIRES (BACK DOOR ECU)
(a) Disconnect the back door ECU connector from the back door ECU.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN JUNCTION CONNECTOR RR - BACK DOOR ECU)
OK -- REPLACE BACK DOOR MOTOR UNIT (BACK DOOR ECU)