Dtc U1002 (Can Ms Bus) Lost Communication With Gateway Module (Main Body Ecu)

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK CAN MS BUS WIRE

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE

CHECK FOR OPEN IN CAN MS BUS WIRE (CAN MS BUS BRANCH WIRE)

CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER MAIN WIRE)

CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU MAIN WIRE)

CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU - CAN NO. 3 JUNCTION CONNECTOR)

CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER - CAN NO. 3 JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN MS BUS WIRES (MAIN BODY ECU MAIN WIRE)

CHECK FOR SHORT IN CAN MS BUS WIRES (COMBINATION METER MAIN WIRE)

CHECK FOR SHORT IN CAN MS BUS WIRES (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

CHECK FOR SHORT IN CAN MS BUS WIRES (CAN No. 3 JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN MS BUS MAIN WIRE (MAIN BODY ECU - CAN NO. 3 JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN MS BUS WIRES (COMBINATION METER - CAN NO. 3 JUNCTION CONNECTOR)

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (COMBINATION METER MAIN WIRE)

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)

CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (COMBINATION METER MAIN WIRE)

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)

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

DESCRIPTION

1. 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.
   
2. 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.
   

DTC No.	DTC Detection Condition	Trouble Area
U1002	Main body ECU cannot receive signals from all ECUs that have been memorized as those connected to the CAN MS bus.	Open or short in CAN MS bus main wire or connector Open or short in CAN MS bus branch wire or connector Certification ECU Combination meter Main body ECU CAN No. 3 junction connector

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:

1. Turn the ignition switch off before measuring the resistance between CAN bus main wires and CAN bus branch wires.
   
2. After the ignition switch is turned off, check that the key reminder warning system and light reminder warning system are not operating.
   
3. 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:

1. 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.
   
2. 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.
   

1.CHECK CAN MS BUS WIRE

1. Turn the ignition switch off.
   

   Text in Illustration

   *a	Component with harness connected (Main Body ECU)

2. Measure the resistance according to the value(s) in the table below.
   
   

   Result:

   
   

   Tester Connection	Switch Condition	Result	Proceed to
   E51-11 (CANP) - E51-12 (CANN)	Ignition switch off	54 to 69 Ω	A
   E51-11 (CANP) - E51-12 (CANN)	Ignition switch off	70 Ω or higher	B
   E51-11 (CANP) - E51-12 (CANN)	Ignition switch off	Less than 54 Ω	C

B	Go to step 5
C	Go to step 9

A

2.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE

1. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1	DLC3
   *a	Component with harness connected (Main Body ECU)

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E51-11 (CANP) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E51-12 (CANN) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

NG	Go to step 15

OK

3.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE

1. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1	DLC3
   *a	Component with harness connected (Main Body ECU)

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E51-11 (CANP) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E51-12 (CANN) - E11-4 (CG)	Ignition switch off	200 Ω or higher

NG	Go to step 20

OK

4.CHECK FOR OPEN IN CAN MS BUS WIRE (CAN MS BUS BRANCH WIRE)

1. Check for open in the certification ECU CAN MS bus branch wire (COROLLA_ZRE142 RM000002E79048X.html).
   

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)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-2 (CANH) - E72-7 (CANL)	Ignition switch off	108 to 132 Ω

NG	Go to step 8

OK

6.CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (MAIN BODY ECU MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-3 (CANH) - E72-8 (CANL)	Ignition switch off	108 to 132 Ω

NG	Go to step 7

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)

1. Reconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Main Body ECU)

2. Disconnect the main body ECU connector from the main body ECU.
   

3. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E51-11 (CANP) - E51-12 (CANN)	Ignition switch off	108 to 132 Ω

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)

8.CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (COMBINATION METER - CAN NO. 3 JUNCTION CONNECTOR)

1. Reconnect the CAN No. 3 junction connector.
   

2. Disconnect the combination meter connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Combination Meter)

3. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E46-13 (TX-) - E46-14 (TX1-)	Ignition switch off	108 to 132 Ω

NG	REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

OK
REPLACE COMBINATION METER ASSEMBLY (COROLLA_ZRE142 RM0000024D7032X.html)

9.CHECK FOR SHORT IN CAN MS BUS WIRES (MAIN BODY ECU MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-3 (CANH) - E72-8 (CANL)	Ignition switch off	108 to 132 Ω

NG	Go to step 13

OK

10.CHECK FOR SHORT IN CAN MS BUS WIRES (COMBINATION METER MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-2 (CANH) - E72-7 (CANL)	Ignition switch off	108 to 132 Ω

NG	Go to step 14

OK

11.CHECK FOR SHORT IN CAN MS BUS WIRES (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

1. Disconnect the certification ECU connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Certification ECU)

2. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

3. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-1 (CANH) - E72-6 (CANL)	Ignition switch off	1 MΩ or higher

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

OK

12.CHECK FOR SHORT IN CAN MS BUS WIRES (CAN No. 3 JUNCTION CONNECTOR)

1. Reconnect the CAN No. 3 junction connector.
   

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Certification ECU)

   NOTICE:

   The resistance must be measured after the main body ECU, combination meter and No. 3 junction connectors are reconnected.

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E36-27 (CANH) - E36-28 (CANL)	Ignition switch off	54 Ω or higher

NG	REPLACE CAN NO. 3 JUNCTION CONNECTOR

OK
REPLACE CERTIFICATION ECU

13.CHECK FOR SHORT IN CAN MS BUS MAIN WIRE (MAIN BODY ECU - CAN NO. 3 JUNCTION CONNECTOR)

1. Disconnect the main body ECU connector from the main body ECU.
   

2. Reconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Main Body ECU)

3. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E51-11 (CANP) - E51-12 (CANN)	Ignition switch off	108 to 132 Ω

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)

14.CHECK FOR SHORT IN CAN MS BUS WIRES (COMBINATION METER - CAN NO. 3 JUNCTION CONNECTOR)

1. Disconnect the combination meter connector.
   

2. Reconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to Combination Meter)

3. Measure the resistance according to the value(s) in the table below.
   

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E46-13 (TX-) - E46-14 (TX1-)	Ignition switch off	108 to 132 Ω

NG	REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

OK
REPLACE COMBINATION METER ASSEMBLY (COROLLA_ZRE142 RM0000024D7032X.html)

15.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E72-3 (CANH) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E72-8 (CANL) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

NG	Go to step 18

OK

16.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (COMBINATION METER MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E72-2 (CANH) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E72-7(CANL) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

NG	Go to step 19

OK

17.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

1. Disconnect the certification ECU connector.
   

2. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

3. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E72-1 (CANH) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E72-6 (CANL) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

NG	REPAIR OR REPLACE CAN MS BUS BRANCH WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

OK
REPLACE CERTIFICATION ECU

18.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)

1. Disconnect the main body ECU connector from the main body ECU.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E72-3 (CANH) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E72-8 (CANL) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

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)

19.CHECK FOR SHORT TO +B IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Disconnect the combination meter connector.
   

3. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Condition	Specified Condition
   E72-2 (CANH) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher
   E72-7 (CANL) - E11-16 (BAT)	Cable is disconnected from negative (-) battery terminal	6 kΩ or higher

NG	REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

OK
REPLACE COMBINATION METER ASSEMBLY (COROLLA_ZRE142 RM0000024D7032X.html)

20.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (MAIN BODY ECU MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-3 (CANH) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E72-8 (CANL) - E11-4 (CG)	Ignition switch off	200 Ω or higher

NG	Go to step 24

OK

21.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (COMBINATION METER MAIN WIRE)

1. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-2 (CANH) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E72-7 (CANL) - E11-4 (CG)	Ignition switch off	200 Ω or higher

NG	Go to step 23

OK

22.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

1. Disconnect the certification ECU connector.
   

2. Disconnect the CAN No. 3 junction connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

3. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-1 (CANH) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E72-6 (CANL) - E11-4 (CG)	Ignition switch off	200 Ω or higher

NG	REPAIR OR REPLACE CAN MS BUS BRANCH WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - CERTIFICATION ECU)

OK
REPLACE CERTIFICATION ECU

23.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

1. Disconnect the combination meter connector.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-2 (CANH) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E72-7 (CANL) - E11-4 (CG)	Ignition switch off	200 Ω or higher

NG	REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 JUNCTION CONNECTOR - COMBINATION METER)

OK
REPLACE COMBINATION METER ASSEMBLY (COROLLA_ZRE142 RM0000024D7032X.html)

24.CHECK FOR SHORT TO GND IN CAN MS BUS WIRE (CAN NO. 3 JUNCTION CONNECTOR - MAIN BODY ECU)

1. Disconnect the main body ECU connector from the main body ECU.
   

   Text in Illustration

   *a	Front view of wire harness connector (to CAN No. 3 Junction Connector)

2. Measure the resistance according to the value(s) in the table below.
   

   Text in Illustration

   *1

   DLC3

   Standard Resistance:

   Tester Connection	Switch Condition	Specified Condition
   E72-3 (CANH) - E11-4 (CG)	Ignition switch off	200 Ω or higher
   E72-8 (CANL) - E11-4 (CG)	Ignition switch off	200 Ω or higher

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)