CAN COMMUNICATION SYSTEM(for LHD), Diagnostic DTC:U0104

DTC Code	DTC Name
U0104	Lost Communication with Cruise Control Module

DESCRIPTION

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	DTC Output from
U0104	Lost Communication with Cruise Control Module	There is no communication from the driving support ECU assembly.	Power source circuit of driving support ECU assembly Driving support ECU assembly ground circuit Driving support ECU assembly CAN branch wire or connector Driving support ECU assembly Engine stop and start ECU	Network gateway ECU

For vehicles with a pre-crash safety system.

WIRING DIAGRAM

Figure 1. w/o Stop and Start System


*1	No. 3 CAN Junction Connector
*2	ECU-IG NO.2
*3	from IG1 NO.2 Relay
*4	Driving Support ECU Assembly

Figure 2. w/ Stop and Start System


*1	No. 3 CAN Junction Connector
*2	Engine Stop and Start ECU
*3	Driving Support ECU Assembly

CAUTION / NOTICE / HINT

Note

Before measuring the resistance of the CAN bus, turn the engine 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 engine 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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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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After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.
DTC check procedure: Turn the engine switch on (IG) and wait at least 21 seconds.
After the repair, perform the CAN bus check and check that all the ECUs and sensors connected to the CAN communication system are displayed.

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Inspect the fuses for circuits related to this system before performing the following procedure.
When replacing the driving support ECU assembly, make sure to replace it with a new one.

Tech Tips

Operating the engine 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

RECONFIRM DTC OUTPUT

Check for DTCs.

Body Electrical > Gateway > Trouble Codes

Tech Tips

If DTC U1002 is output from the gateway of the network gateway ECU, this indicates a sub bus 2 malfunction. Troubleshoot for DTC U1002 and check for malfunctions in sub bus 2.

Result

Result	Proceed to
U1002 is not output from network gateway ECU	A
U1002 is output from network gateway ECU	B

GO TO DIAGNOSIS PROCEDURE INDICATED BY OUTPUT DTC Click here

CHECK FOR OPEN IN CAN BUS WIRE (DRIVING SUPPORT ECU ASSEMBLY BRANCH WIRE)

*a
Rear view of wire harness connector

(to Driving Support ECU Assembly)

Disconnect the cable from the negative (-) battery terminal.
Disconnect the driving support ECU assembly connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
I19-39 (CA2H) - I19-17 (CA2L)	Cable disconnected from negative (-) battery terminal	54 to 69 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE CAN BRANCH WIRE OR CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY)

CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY - BODY GROUND)

*a
Rear view of wire harness connector

(to Driving Support ECU Assembly)

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

Note

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

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

Standard Resistance

Tester Connection	Condition	Specified Condition
I19-25 (GND) - Body ground	Always	Below 1 Ω

Result

Proceed to
OK
NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY - BATTERY)

*a	Rear view of wire harness connector (to Driving Support ECU Assembly)

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

Standard Voltage

w/o Stop and Start System
Tester Connection	Switch Condition	Specified Condition
I19-30 (B) - Body ground	Engine switch on (IG)	11 to 14 V

w/ Stop and Start System
Tester Connection	Switch Condition	Specified Condition
I19-30 (B) - Body ground	Engine switch on (IG)	10.5 to 16 V

Result

Result	Proceed to
OK	A
NG (w/o Stop and Start System)	B
NG (w/ Stop and Start System)	C

REPLACE DRIVING SUPPORT ECU ASSEMBLY Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR

CHECK HARNESS AND CONNECTOR (DRIVING SUPPORT ECU ASSEMBLY - ENGINE STOP AND START ECU)

Disconnect the I57 engine stop and start ECU connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
I19-30 (B) - I57-12 (IGO1)	Always	Below 1 Ω
I19-30 (B) or I57-12 (IGO1) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

GO TO STOP AND START SYSTEM Click here

REPAIR OR REPLACE HARNESS OR CONNECTOR