CAN COMMUNICATION SYSTEM(w/ Central Gateway ECU), Diagnostic DTC:U1002

DTC Code	DTC Name
U1002	Lost Communication with Gateway Module

DESCRIPTION

The main body ECU (multiplex network body ECU) stores this DTC when no signals can be received from the ECUs that have been memorized as those connected to the sub bus 1.
When the main body ECU (multiplex network body ECU) receives a response signal from the ECUs connected to the sub bus 1, the main body ECU (multiplex network body ECU) recognizes and memorizes that the ECU is connected to the sub bus 1. Based on this memorized data, the main body ECU (multiplex network body ECU) monitors for malfunctions in the ECUs connected to the sub bus 1 when communicating with those ECUs. If the main body ECU (multiplex network body ECU) cannot receive response signals from the ECUs that have been memorized as those connected to the sub bus 1, the main body ECU (multiplex network body ECU) determines that a malfunction exists.
If 2 or more DTCs are output during the DTC check, one side of the CAN branch wire may be open (one side of the CANH [CAN branch wire]/CANL [CAN branch wire] of the ECU and/or sensor is open).

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from
U1002	Lost Communication with Gateway Module	Lost communication with the gateway module.	Open or short in sub bus 1 CAN main wire or connector Open or short in sub bus 1 CAN branch wire or connector Main body ECU (multiplex network body ECU) Front power seat switch (power seat control ECU) (w/ Seat Memory) Outer mirror control ECU assembly LH (w/ Reverse Shift-linked Mirror) Outer mirror control ECU assembly RH (w/ Reverse Shift-linked Mirror) Multiplex tilt and telescopic ECU (for Power Tilt and Power Telescopic Steering Column) Rear television camera assembly (w/ Multi-terrain Monitor System) No. 4 CAN junction connector No. 2 CAN junction terminal	Main body ECU (multiplex network body ECU)

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

When performing the confirmation driving pattern, obey all speed limits and traffic laws.

Note

Because the order of diagnosis is important to allow correct diagnosis, make sure to begin troubleshooting using How to Proceed with Troubleshooting when CAN communication system related DTCs are output.

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Before measuring the resistance of the CAN bus, turn the ignition switch off and leave the vehicle for 1 minute or more without operating the key or any switches, or opening or closing the doors. After that, disconnect the cable from the negative (-) battery terminal and leave the vehicle for 1 minute or more before measuring the resistance.
After turning the ignition switch off, waiting time may be required before disconnecting the cable from the negative (-) battery terminal. Therefore, make sure to read the disconnecting the cable from the negative (-) battery terminal notices before proceeding with work.

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Some parts must be initialized and set when replacing or removing and installing parts.

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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

DTC check procedure: Turn the ignition switch to ON and wait for 1 minute or more. Then operate the suspected malfunctioning system and drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed as normal.

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Tech Tips

Before disconnecting related connectors for inspection, push in on each connector body to check that the connector is not loose or disconnected.
When a connector is disconnected, check that the terminals and connector body are not cracked, deformed or corroded.

PROCEDURE

CHECK SUB BUS 1

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

Component with harness connected

(No. 2 CAN Junction Terminal)

Front view of DLC3

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Resistance: Malfunction
G299-3 (CANP) - G299-2 (CANN)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω	Below 53 Ω: Short in line
G299-3 (CANP) - G299-2 (CANN)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω	Higher than 70 Ω: Open in CAN main bus line
G299-3 (CANP) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: +B short
G299-2 (CANN) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: +B short
G299-3 (CANP) - G299-1 (E)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: Ground short
G299-2 (CANN) - G299-1 (E)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: Ground short

Result

Result	Proceed to
OK	A
NG - Open in CAN main wire	B
NG - Short in CAN bus wire	C
NG - +B short - Ground short	D

CHECK FOR OPEN IN CAN BUS WIRE (NO. 4 CAN JUNCTION CONNECTOR) Click here

CHECK FOR SHORT IN CAN BUS WIRES (NO. 4 CAN JUNCTION CONNECTOR) Click here

CHECK FOR DTC

Reconnect the cable to the negative (-) battery terminal.

Note

When disconnecting the cable, some systems need to be initialized after the cable is reconnected.

Click here
Clear the DTCs.

Check for DTCs.

Result

Result	Proceed to
DTC U1002 is output from main body ECU (multiplex network body ECU)	A
Other DTC is output	B

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

GO TO DIAGNOSTIC TROUBLE CODE CHART Click here

CHECK FOR OPEN IN CAN BUS WIRE (NO. 4 CAN JUNCTION CONNECTOR)

Front view of wire harness connector

(to No. 4 CAN Junction Connector)

to Main Body ECU (Multiplex Network Body ECU)

to No. 2 CAN Junction Terminal

Disconnect the No. 4 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
G288-4 (CANH) - G288-15 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Main body ECU (multiplex network body ECU)
G288-7 (CANH) - G288-18 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 CAN junction terminal

Result

Result	Proceed to
OK	A
NG (Main body ECU [multiplex network body ECU] CAN main wire)	B
NG (No. 2 CAN junction terminal CAN main wire)	C

REPLACE NO. 4 CAN JUNCTION CONNECTOR

CONNECT CONNECTOR Click here

CONNECT CONNECTOR

Reconnect the G288 No. 4 CAN junction connector.

Result

Proceed to
NEXT

CHECK FOR OPEN IN CAN BUS WIRE (MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] - NO. 4 CAN JUNCTION CONNECTOR)

*a
Front view of wire harness connector

(to Main Body ECU [Multiplex Network Body ECU])

Disconnect the main body ECU (multiplex network body ECU) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G216-9 (CANP) - G216-10 (CANN)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Proceed to
OK
NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] - NO. 4 CAN JUNCTION CONNECTOR)

CONNECT CONNECTOR

Reconnect the G288 No. 4 CAN junction connector.

Result

Proceed to
NEXT

CHECK FOR OPEN IN CAN BUS WIRE (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

*a
Rear view of wire harness connector

(to No. 2 CAN Junction Terminal)

Disconnect the No. 2 CAN junction terminal connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G299-3 (CANP) - G299-2 (CANN)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Proceed to
OK
NG

REPLACE NO. 2 CAN JUNCTION TERMINAL

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS WIRES (NO. 4 CAN JUNCTION CONNECTOR)

*a	Front view of wire harness connector (to No. 4 CAN Junction Connector)
*b	to Outer Mirror Control ECU Assembly RH (w/ Reverse Shift-linked Mirror)
*c	to Front Power Seat Switch (Power Seat Control ECU) (w/ Seat Memory)
*d	to Multiplex Tilt and Telescopic ECU (for Power Tilt and Power Telescopic Steering Column)
*e	to Main Body ECU (Multiplex Network Body ECU)
*f	to Rear Television Camera Assembly (w/ Multi-terrain Monitor System)
*g	to Outer Mirror Control ECU Assembly LH (w/ Reverse Shift-linked Mirror)
*h	to No. 2 CAN Junction Terminal

Disconnect the No. 4 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
G288-1 (CANH) - G288-12 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly RH*4
G288-2 (CANH) - G288-13 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Front power seat switch (power seat control ECU)*1
G288-3 (CANH) - G288-14 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Multiplex tilt and telescopic ECU*2
G288-4 (CANH) - G288-15 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	Main body ECU (multiplex network body ECU)
G288-5 (CANH) - G288-16 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Rear television camera assembly*3
G288-6 (CANH) - G288-17 (CANL)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly LH*4
G288-7 (CANH) - G288-18 (CANL)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	No. 2 CAN junction terminal

*1: w/ Seat Memory
*2: for Power Tilt and Power Telescopic Steering Column
*3: w/ Multi-terrain Monitor System
*4: w/ Reverse Shift-linked Mirror

Result

Result	Proceed to
OK	A
NG (Main body ECU [multiplex network body ECU] CAN main wire)	B
NG (No. 2 CAN junction terminal CAN main wire)	C
NG (Wire to ECU or sensor)	D

REPLACE NO. 4 CAN JUNCTION CONNECTOR

CONNECT CONNECTOR Click here

GO TO STEP 16 Click here

CONNECT CONNECTOR

Reconnect the G288 No. 4 CAN junction connector.

Result

Proceed to
NEXT

CHECK FOR SHORT IN CAN BUS WIRES (MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] - NO. 4 CAN JUNCTION CONNECTOR)

*a
Front view of wire harness connector

(to Main Body ECU [Multiplex Network Body ECU])

Disconnect the main body ECU (multiplex network body ECU) connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G216-9 (CANP) - G216-10 (CANN)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Proceed to
OK
NG

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Click here

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (MAIN BODY ECU [MULTIPLEX NETWORK BODY ECU] - NO. 4 CAN JUNCTION CONNECTOR)

CONNECT CONNECTOR

Reconnect the G288 No. 4 CAN junction connector.

Result

Proceed to
NEXT

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

*a
Rear view of wire harness connector

(to No. 2 CAN Junction Terminal)

Disconnect the No. 2 CAN junction terminal connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G299-3 (CANP) - G299-2 (CANN)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

Result

Proceed to
OK
NG

REPLACE NO. 2 CAN JUNCTION TERMINAL

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS WIRES (NO. 4 CAN JUNCTION CONNECTOR)

*a	Front view of wire harness connector (to No. 4 CAN Junction Connector)
*b	Front view of DLC3
*c	to Outer Mirror Control ECU Assembly RH (w/ Reverse Shift-linked Mirror)
*d	to Front Power Seat Switch (Power Seat Control ECU) (w/ Seat Memory)
*e	to Multiplex Tilt and Telescopic ECU (for Power Tilt and Power Telescopic Steering Column)
*f	to Main Body ECU (Multiplex Network Body ECU)
*g	to Rear Television Camera Assembly (w/ Multi-terrain Monitor System)
*h	to Outer Mirror Control ECU Assembly LH (w/ Reverse Shift-linked Mirror)
*i	to No. 2 CAN Junction Terminal

Disconnect the No. 4 CAN junction connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition	Connected to
G288-1 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly RH*4
G288-12 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-1 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-12 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-2 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Front power seat switch (power seat control ECU)*1
G288-13 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-2 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-13 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-3 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Multiplex tilt and telescopic ECU*2
G288-14 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-3 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-14 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-4 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Main body ECU (multiplex network body ECU)
G288-15 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-4 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-15 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-5 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Rear television camera assembly*3
G288-16 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-5 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-16 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-6 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Outer mirror control ECU assembly LH*4
G288-17 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-6 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-17 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-7 (CANH) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher	No. 2 CAN junction terminal
G288-18 (CANL) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G288-7 (CANH) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G288-18 (CANL) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

*1: w/ Seat Memory
*2: for Power Tilt and Power Telescopic Steering Column
*3: w/ Multi-terrain Monitor System
*4: w/ Reverse Shift-linked Mirror

Result

Result	Proceed to
OK	A
NG (No. 2 CAN junction terminal CAN main wire)	B
NG (Wire to ECU or sensor)	C

REPLACE NO. 4 CAN JUNCTION CONNECTOR

CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR) Click here

CONNECT CONNECTOR

Reconnect the G288 No. 4 CAN junction connector.

Result

Proceed to
NEXT

CHECK FOR SHORT IN CAN BUS WIRES (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

Rear view of wire harness connector

(to No. 2 CAN Junction Terminal)

Front view of DLC3

Disconnect the No. 2 CAN junction terminal connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G299-3 (CANP) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G299-2 (CANN) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G299-3 (CANP) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G299-2 (CANN) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Result

Proceed to
OK
NG

REPLACE NO. 2 CAN JUNCTION TERMINAL

REPAIR OR REPLACE CAN BUS MAIN WIRE OR CONNECTOR (NO. 2 CAN JUNCTION TERMINAL - NO. 4 CAN JUNCTION CONNECTOR)

CHECK FOR SHORT IN CAN BUS WIRES (ECU, SENSOR)

Reconnect the wire harness connectors.

Rear view of wire harness connector

(to No. 2 CAN Junction Terminal)

Front view of DLC3

Disconnect the connector that includes terminals CANH and CANL from the ECU or sensor to which the short circuited main/branch line is connected.

Click here

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

Standard Resistance

Tester Connection	Condition	Specified Condition
G299-3 (CANP) - G299-2 (CANN)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω
G299-3 (CANP) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G299-2 (CANN) - G48-4 (CG)	Cable disconnected from negative (-) battery terminal	200 Ω or higher
G299-3 (CANP) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
G299-2 (CANN) - G48-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Tech Tips

If the resistance becomes normal (between 54 and 69 Ω) when the connector is disconnected from the ECU or sensor, there may be a short to CAN bus lines in the ECU or sensor.
If the resistance changes to 6 kΩ or higher when the connector is disconnected from the ECU or sensor, there may be a short to B+ in the ECU or sensor.
If the resistance changes to 200 Ω or higher when the connector is disconnected from the ECU or sensor, there may be a short to GND in the ECU or sensor.
If the resistance does not become normal when the connector is disconnected from the ECU or sensor, check for a short circuit in the wire harness and repair or replace the wire harness or connector if necessary.

Result

Proceed to
OK
NG

REPLACE ECU OR SENSOR

REPAIR OR REPLACE HARNESS OR CONNECTOR