Part 1
NETWORKING: CAN COMMUNICATION SYSTEM: U1002 (CAN MS BUS); Lost Communication with Gateway Module (Main body ECU); 2013 MY Corolla [07/2012 -]
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 resistance between 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 operating.
* 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 the 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 may help determine the cause of the malfunction.
PROCEDURE
1. CHECK CAN MS BUS WIRE
(a) Turn the ignition switch off.
Text in Illustration
(b) Measure the resistance according to the value(s) in the table below.
Result:
B -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER MAIN WIRE)
C -- CHECK FOR SHORT IN CAN MS BUS WIRES (MAIN BODY ECU MAIN WIRE)
A -- Continue to next step.
2. CHECK FOR SHORT TO +B IN CAN MS BUS WIRE
(a) Measure the resistance according to the value(s) in the table below.
Text in Illustration
Standard Resistance:
NG -- CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)
OK -- Continue to next step.
3. CHECK FOR SHORT TO GND IN CAN MS BUS WIRE
(a) Measure the resistance according to the value(s) in the table below.
Text in Illustration
Standard Resistance:
NG -- CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)
OK -- Continue to next step.
4. CHECK FOR OPEN IN CAN MS BUS WIRE (CAN MS BUS BRANCH WIRE)
(a) Check for open in the certification ECU CAN MS bus branch wire U0327.
NG -- REPAIR OR REPLACE CAN MS BUS BRANCH WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK (MAIN BODY ECU)
5. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER MAIN WIRE)
(a) Disconnect the CAN No. 3 junction connector.
Text in Illustration
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER - CAN NO. 3 JUNCTION CONNECTOR)
OK -- Continue to next step.
6. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU MAIN WIRE)
(a) Disconnect the CAN No. 3 junction connector.
Text in Illustration
(b) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
NG -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU - CAN NO. 3 JUNCTION CONNECTOR)
OK -- REPLACE CAN NO. 3 JUNCTION CONNECTOR
7. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU - CAN NO. 3 JUNCTION CONNECTOR)
(a) Reconnect the CAN No. 3 junction connector.
Text in Illustration
(b) Disconnect the main body ECU connector from the main body ECU.
(c) 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 (CAN NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)
OK -- REPLACE INSTRUMENT PANEL JUNCTION BLOCK (MAIN BODY ECU)