U1002 - Lost Communication with Gateway Module (Main Body)

NETWORKING: CAN COMMUNICATION SYSTEM: U1002: Lost Communication with Gateway Module (Main Body)
U1002 - Lost Communication with Gateway Module (Main Body)

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.

HINT
The diagnosis procedure is for when DTC U1002 is output by the main body ECU (Techstream display: Main Body).

WIRING DIAGRAM

INSPECTION PROCEDURE

NOTICE:
* Turn the power switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
* Turn the power switch off before inspecting CAN bus wires for a ground short.
* After the power 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 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 may 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:

(c) Disconnect the cable from the negative (-) battery terminal.

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

Standard Resistance:

Text in Illustration

Result:

E -- CHECK FOR SHORT IN CAN MS BUS WIRE (CAN NO. 3 J/C - MAIN BODY ECU)

D -- CHECK FOR SHORT IN CAN MS BUS WIRES (CAN NO. 3 J/C - MAIN BODY ECU)

C -- CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN NO. 3 J/C - MAIN BODY ECU)

B -- CHECK CAN BUS BRANCH WIRE AND POWER SOURCE CIRCUIT (TIRE PRESSURE MONITOR ECU)
A -- Continue to next step.

2. CHECK RECONFIRM DTC OUTPUT (MAIN BODY ECU)

(a) Clear the DTC.

(b) Turn the power switch off.

(c) Turn the power switch on (IG), recheck the DTC.

Result:

B -- GO TO CIRCUITS INDICATED BY OUTPUT DTCS

A -- REPLACE MULTIPLEX NETWORK BODY ECU (MAIN BODY ECU) Removal

3. CHECK CAN BUS BRANCH WIRE AND POWER SOURCE CIRCUIT (TIRE PRESSURE MONITOR ECU)

(a) Check the tire pressure monitor ECU branch wire and ECU power source circuit U0127.

OK:

Tire pressure monitor ECU branch wire and ECU power source circuit is normal.

NG -- REPAIR WIRE HARNESS AND CONNECTOR
OK -- Continue to next step.

4. CHECK DTC OUTPUT (TIRE PRESSURE WARNING SYSTEM)

(a) Check the DTC from the tire pressure monitor ECU Reading and Clearing Diagnostic Trouble Codes.

Result:

B -- GO TO CIRCUITS INDICATED BY OUTPUT DTCS

A -- REPLACE MULTIPLEX NETWORK BODY ECU (MAIN BODY ECU) Removal

5. CHECK FOR OPEN IN CAN MS BUS MAIN WIRE (CAN NO. 3 J/C - MAIN BODY ECU)

(a) Disconnect the main body ECU main wire harness connector from 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)

OK -- REPLACE CAN NO. 3 JUNCTION CONNECTOR

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

(a) Reconnect the main body ECU main wire harness connector to the CAN No. 3 junction connector.

(b) Disconnect the main body ECU connector.

Text in Illustration

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 J/C - MAIN BODY ECU)

OK -- REPLACE MULTIPLEX NETWORK BODY ECU (MAIN BODY ECU) Removal

7. CHECK FOR SHORT IN CAN MS BUS WIRES (CAN NO. 3 J/C - MAIN BODY ECU)

(a) Disconnect the main body ECU main wire harness connector from 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 SHORT IN CAN MS BUS WIRES (MAIN BODY ECU)
OK -- Continue to next step.

8. CHECK FOR SHORT IN CAN MS BUS WIRE (CAN NO. 3 J/C)

(a) Reconnect the main body ECU main wire harness connector to the CAN No. 3 junction connector.

Text in Illustration

(b) Connect the probes of an ohmmeter to terminals 1(CANH) and 2 (CANL) of the main body ECU main wire harness connector.

(c) While observing the resistance value shown on the ohmmeter, disconnect branch wire connectors (except F84 and F86) from the CAN No. 3 junction connector until the resistance becomes normal (between 54 and 69 Ohms).

Text in Illustration

Junction Connector B Side

Junction Connector A Side

Result:

B -- CHECK FOR SHORT IN CAN MS BUS WIRE (ECU)

A -- REPLACE CAN NO. 3 JUNCTION CONNECTOR

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

(a) Reconnect the connector for the short-circuited branch wire to the CAN junction connector (the connector that caused the bus wire resistance to become normal (between 54 and 69 Ohms) when it was disconnected).

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU to which the short-circuited branch wire is connected.

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

Standard Resistance:

Text in Illustration

HINT
If the resistance becomes normal (between 54 and 69 Ohms) when the connector is disconnected from the ECU, there may be a short in the ECU.

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR

OK -- REPLACE CORRESPONDING ECU OR SWITCH

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

(a) Reconnect the main body ECU main wire harness connector to the CAN No. 3 junction connector.

(b) Disconnect the main body ECU connector.

Text in Illustration

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 J/C - MAIN BODY ECU)

OK -- REPLACE MULTIPLEX NETWORK BODY ECU (MAIN BODY ECU) Removal

11. CHECK FOR SHORT IN CAN MS BUS WIRE (CAN NO. 3 J/C - MAIN BODY ECU)

(a) Disconnect the main body ECU main wire harness connector from the CAN No. 3 junction connector.

Text in Illustration

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

Standard Resistance:

Inspection for CAN Ground Short

Inspection for CAN +B Short

HINT
It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN MS Bus Wire inspection.

NG -- CHECK FOR SHORT IN CAN MS BUS WIRE (MAIN BODY ECU)
OK -- Continue to next step.

12. CHECK FOR SHORT IN CAN MS BUS WIRE (CAN NO. 3 J/C)

(a) Reconnect the main body ECU main wire harness connector to the CAN No. 3 junction connector.

Text in Illustration

(b) Connect the probes of an ohmmeter to terminals CANH or CANL of the power management control ECU and CG or BAT of the DLC3.

HINT
It is only necessary to perform the inspection for the result (short circuit) that was obtained in the Check CAN No. 2 Bus Wire inspection.

(c) While observing the resistance value shown on the ohmmeter, disconnect branch wire connector (except F84 and F86) from the CAN No. 3 junction connector until the resistance becomes normal (6 kOhms or higher (for +B short) or 200 Ohms or higher (for ground short)).

Text in Illustration

Junction Connector B Side

Junction Connector A Side

Result:

B -- CHECK FOR SHORT IN CAN MS BUS WIRE (ECUS)

A -- REPLACE CAN NO. 3 JUNCTION CONNECTOR

13. CHECK FOR SHORT IN CAN MS BUS WIRE (ECUS)

(a) Reconnect the connector for the bus wire that is shorted to +B or GND to the CAN junction connector (the connector that caused the bus wire resistance to change to 6 kOhms or higher (for +B short) or 200 Ohms or higher (for ground short) when it was disconnected).

(b) Disconnect the connector that includes terminals CANH and CANL from the ECU to which the bus wire shorted to +B or GND is connected.

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

HINT
It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN No. 2 Bus Wire inspection.

Standard Resistance:

Inspection for CAN Ground Short

Inspection for CAN +B Short

Text in Illustration

HINT
If the resistance becomes normal when the connector is disconnected from the ECU, there may be a short in the ECU.

NG -- REPAIR OR REPLACE CORRESPONDING ECU OR SENSOR BRANCH WIRE OR CONNECTOR

OK -- REPLACE CORRESPONDING ECU OR SWITCH

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

(a) Disconnect the main body ECU connector.

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

Standard Resistance:

Inspection for CAN Ground Short

Inspection for CAN +B Short

HINT
It is only necessary to perform the inspection in the above table for the result (short circuit) that was obtained in the Check CAN MS Bus Wire inspection.

Text in Illustration

NG -- REPAIR OR REPLACE CAN MS BUS MAIN WIRE OR CONNECTOR (CAN NO. 3 J/C - MAIN BODY ECU)

OK -- REPLACE MULTIPLEX NETWORK BODY ECU (MAIN BODY ECU) Removal