Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open in Bus 1 Main Bus Line

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 1 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the bus 1 main lines when the resistance between terminals 23 (CA1H) and 8 (CA1L) of the network gateway ECU is 70 Ω or higher.

Symptom

Trouble Area

Resistance between terminals 23 (CA1H) and 8 (CA1L) of network gateway ECU is 70 Ω or higher.
  • CAN main bus line or connector
  • Network gateway ECU
  • No. 3 CAN junction connector
  • No. 10 CAN junction connector

This malfunction is not related to the lines of a bus 1 branch or to ECUs or sensors connected to a bus 1 branch.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

CAUTION:

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

NOTICE:

  • 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 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.

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HINT:

  • 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

1.

CHECK FOR OPEN IN CAN BUS LINES (NO. 10 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the S56 and S57 No. 10 CAN junction connectors.

HINT:

  • Connectors that connect to the CAN junction connector can be distinguished by the color of their CAN bus lines.
  • Before disconnecting the connectors, make a note of where they are connected.
  • Reconnecting the connectors to non-original positions on the CAN junction connector does not affect system performance. However, it is preferred to reconnect the connectors to their original positions to avoid negative effects on the wiring such as tension on the wiring harnesses, and to make future maintenance easier.

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

*a

Rear view of wire harness connector

(to No. 10 CAN Junction Connector)

*b

to Network Gateway ECU

*c

to No. 3 CAN Junction Connector

-

-
Wiring Color:

Code

Color (CANH Side)

Color (CANL Side)

Connected to

S56

G

W

Network gateway ECU

S57

LG

W

No. 3 CAN junction connector

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

S56-1 (CANH) - S56-2 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Network gateway ECU

S57-1 (CANH) - S57-2 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

No. 3 CAN junction connector

Result

Proceed to

OK

A

NG (No. 3 CAN junction connector main lines)

B

NG (Network gateway ECU main lines)

C
A

REPLACE NO. 10 CAN JUNCTION CONNECTOR
C

GO TO STEP 4

B

2.

CHECK FOR OPEN IN CAN BUS LINES (NO. 3 CAN JUNCTION CONNECTOR)

(a) Reconnect the S56 and S57 No. 10 CAN junction connectors.

(b) Disconnect the J95 No. 3 CAN junction connector.

*a

Front view of wire harness connector

(to No. 3 CAN Junction Connector)

*b

to Network Gateway ECU

*c

to No. 10 CAN Junction Connector

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

J95-1 (CANH) - J95-11 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Network gateway ECU

J95-10 (CANH) - J95-20 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

No. 10 CAN junction connector

Result

Proceed to

OK

A

NG (No. 10 CAN junction connector main lines)

B

NG (Network gateway ECU main lines)

C
A

REPLACE NO. 3 CAN JUNCTION CONNECTOR
B

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NO. 3 CAN JUNCTION CONNECTOR - NO. 10 CAN JUNCTION CONNECTOR)
C

3.

CHECK FOR OPEN IN CAN BUS LINES (NETWORK GATEWAY ECU - NO. 3 CAN JUNCTION CONNECTOR)

(a) Reconnect the J95 No. 3 CAN junction connector.

(b) Disconnect the J75 network gateway ECU connector.

*a

Front view of wire harness connector

(to Network Gateway ECU)

*b

to No. 3 CAN Junction Connector

*c

to No. 10 CAN Junction Connector

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J75-9 (CAXH) - J75-23 (CA1H)

Cable disconnected from negative (-) battery terminal

Below 1 Ω

J75-8 (CA1L) - J75-24 (CAXL)

Cable disconnected from negative (-) battery terminal

Below 1 Ω
OK

REPLACE NETWORK GATEWAY ECU

NG

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NETWORK GATEWAY ECU - NO. 3 CAN JUNCTION CONNECTOR)

4.

CHECK FOR OPEN IN CAN BUS LINES (NETWORK GATEWAY ECU - NO. 10 CAN JUNCTION CONNECTOR)

(a) Reconnect the S56 and S57 No. 10 CAN junction connectors.

(b) Disconnect the J75 network gateway ECU connector.

*a

Front view of wire harness connector

(to Network Gateway ECU)

*b

to No. 3 CAN Junction Connector

*c

to No. 10 CAN Junction Connector

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J75-9 (CAXH) - J75-23 (CA1H)

Cable disconnected from negative (-) battery terminal

Below 1 Ω

J75-8 (CA1L) - J75-24 (CAXL)

Cable disconnected from negative (-) battery terminal

Below 1 Ω
OK

REPLACE NETWORK GATEWAY ECU

NG

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NETWORK GATEWAY ECU - NO. 10 CAN JUNCTION CONNECTOR)
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