CAN COMMUNICATION SYSTEM

VEHICLE BROUGHT TO WORKSHOP

CUSTOMER PROBLEM ANALYSIS

Interview the customer and confirm the problem.

NEXT

CHECK BATTERY

Standard Voltage
11 to 14 V

Tech Tips

If the voltage is below 11 V, recharge or replace the battery before proceeding to the next step.

CHECK AND CLEAR DTCS*

Tech Tips

CAN communication DTCs are stored when there is an open or short in any of the communication wires. Any problems with the power source of a corresponding ECU or sensor, or problems in the ECU or the sensor itself also cause these DTCs to be stored.
If a CAN communication wire connector is disconnected with the ignition switch ON, the ECUs of the corresponding system and related systems store a DTC.

CHECK DLC3 BRANCH WIRE AND CAN NO. 1 BUS MAIN WIRE (CANH - CANL)

Note

Turn the ignition switch off before measuring the resistances between CAN bus main wires and between CAN bus branch wires.
Turn the ignition switch off before inspecting CAN bus wires for a ground short.
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 connectors, open the doors and leave them open.

Tech Tips

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.

Turn the ignition switch off.

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
D1-6 (CANH) - D1-14 (CANL)	Ignition switch off	54 to 69 Ω

Text in Illustration
*1	DLC3

Result

Result	Proceed to
OK	A
NG (70 Ω or higher)	B
NG (Below 54 Ω)	C

B

GO TO OPEN IN CAN MAIN BUS WIRE Click here

C

GO TO SHORT IN CAN BUS LINES Click here

A

CHECK FOR SHORT TO GND IN CAN NO. 1 BUS (CANH, CANL - CG)

Turn the ignition switch off.

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

Standard Resistance

Tester Connection	Switch Condition	Specified Condition
D1-6 (CANH) - D1-4 (CG)	Ignition switch off	200 Ω or higher
D1-14 (CANL) - D1-4 (CG)	Ignition switch off	200 Ω or higher

Text in Illustration
*1	DLC3

NG

GO TO SHORT TO GND IN CAN BUS LINE Click here

OK

CHECK FOR SHORT TO +B IN CAN NO. 1 BUS (CANH, CANL - BAT)

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
D1-6 (CANH) - D1-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
D1-14 (CANL) - D1-16 (BAT)	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

Text in Illustration
*1	DLC3

NG

GO TO SHORT TO +B IN CAN BUS LINE Click here

OK

CHECK INSTALLED SYSTEMS (ECU AND SENSOR) THAT USE CAN COMMUNICATION

Based on the vehicle equipment and specifications, confirm the systems that use CAN communication Click here.

NEXT

CHECK ECUS CONNECTED TO CAN BUS*

Select "CAN Bus Check" from the screen on the GTS Click here.

Observe the screen for approximately 1 minute to check the ECUs and sensors displayed on the screen.

Result

Result	Proceed to
All ECUs and sensors connected to the CAN communication system are displayed on the screen. (CAN bus circuit is currently normal.)	A
All ECUs except the main body ECU (driver side junction block assembly) connected to the CAN MS bus are not displayed on the screen. The main body ECU (driver side junction block assembly) outputs DTC U1002. (Open or short in CAN MS bus main wires.)	B*1
All ECUs connected to the CAN MS bus are not displayed on the screen. (Open in main body ECU (driver side junction block assembly) branch wire or main body ECU (driver side junction block assembly) malfunction.)	C
All ECUs except the power management control ECU connected to the power management bus are not displayed on the screen. The power management control ECU (PM1 Gateway) outputs DTC U1002. (Open or short in power management bus main wires.)	D*1
All ECUs except the power management control ECU connected to the power management bus are not displayed on the screen. The power management control ECU (PM2 Gateway) outputs DTC U1002. (Open or short in power management bus main wires.)	E*1
All ECUs connected to the CAN No. 2 bus and power management bus are not displayed on the screen. (Open in power management control ECU branch wires or power management control ECU malfunction.)	F
One of the ECUs and sensors connected to the CAN communication system is not displayed on the screen. (Open in ECU or sensor branch wires, or communication interrupted.)	G
Some ECUs and sensors repeatedly appear and disappear on the screen during this check. (Open in one side of ECU or sensor branch wires.)	H

Note

The systems (ECUs and sensors) that adopt CAN communication vary depending on the vehicle and optional equipment. Check which systems (ECUs and sensors) are installed on the vehicle Click here.
Non-installed ECUs or sensors will not be displayed. Do not mistake them for being in the communication stop mode.
The ECUs and sensors that repeatedly appear and disappear from the screen during this check are considered normal. (The response to the GTS and its display are affected by signals output from other ECUs which have an open circuit in either of their CAN bus branch wires.)

Tech Tips

*1: See Diagnostic Trouble Code Chart instead of Communication Stop Mode Table when some of the ECUs connected to the CAN MS bus, power management bus and CAN No. 2 bus are not displayed on the screen Click here.
The ECUs connected to the CAN MS bus are displayed on the screen by the main body ECU (driver side junction block assembly).
The ECUs connected to the CAN No. 2 bus and power management bus are displayed on the screen by the power management control ECU.

B

GO TO U1002 (MS BUS) Click here

C

GO TO MAIN BODY ECU COMMUNICATION STOP MODE Click here

D

GO TO U1002 (CAN NO. 2 BUS) Click here

E

GO TO U1002 (POWER MANAGEMENT BUS)

F

GO TO POWER MANAGEMENT CONTROL ECU COMMUNICATION STOP MODE Click here

G

GO TO COMMUNICATION STOP MODE TABLE Click here

H

GO TO OPEN IN ONE SIDE OF CAN BRANCH LINE Click here

A

RECHECK DTC*

Tech Tips

Sometimes CAN communication system DTCs are output, but all ECUs and sensors connected to the CAN communication system are displayed on the GTS. In this case, previous or history DTCs may indicate the cause of the problem.
ECUs related to a problem in the CAN bus will store DTCs to indicate communication malfunctions. The communication stop mode in the CAN bus can be determined by comparing the combination of DTCs that have been set. Refer to DTC Combination Table for the CAN bus.
The main body ECU (driver side junction block assembly) will store communication error DTCs when the ECUs connected to the CAN MS bus cannot communicate, or if a network malfunction occurs.
The power management control ECU will store communication error DTCs when the ECUs connected to the CAN No. 2 bus and power management bus cannot communicate, or if a network malfunction occurs.

Result

Result	Proceed to
Communication error DTCs other than the codes output from the main body ECU (driver side junction block assembly) and/or power management control ECU is output. (A malfunction occurred in the CAN No. 1 bus.)	A
The main body ECU (driver side junction block assembly) outputs DTC. (A malfunction occurred in the CAN MS bus.)	B
The power management control ECU (PM1 Gateway) outputs DTC. (A malfunction occurred in the CAN No. 2 bus.)	C
The power management control ECU (PM2 Gateway) outputs DTC. (A malfunction occurred in the power management bus.)	D

B

GO TO U1002 (MS BUS) Click here

C

GO TO U1002 (CAN NO. 2 BUS) Click here

D

GO TO U1002 (POWER MANAGEMENT BUS) Click here

A

DTC COMBINATION TABLE

Confirm trouble according to the combination of output DTCs regarding the CAN communication system Click here.

Tech Tips

Previous CAN communication system DTCs may be the cause if CAN communication system DTCs are output and all ECUs and sensors connected to the CAN communication system are displayed on "CAN Bus Check" of the GTS.

NEXT

CIRCUIT INSPECTION

IDENTIFICATION OF PROBLEM

REPAIR OR REPLACEMENT

CONFIRMATION TEST*

END

CAN COMMUNICATION SYSTEM HOW TO PROCEED WITH TROUBLESHOOTING