Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open in Bus 5 Main Bus Line

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 5 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the bus 5 main lines when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the network gateway ECU is 70 Ω or higher.

Symptom

Trouble Area

Resistance between terminals 15 (CA5H) and 16 (CA5L) of network gateway ECU is 70 Ω or higher.
  • CAN main bus line or connector
  • Network gateway ECU
  • Combination meter assembly
  • No. 5 CAN junction connector

This malfunction is not related to the lines of a bus 5 branch or to ECUs or sensors connected to a bus 5 branch.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

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: Drive the vehicle at a speed of 5 km/h (3 mph) or more for 52 seconds 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 (NETWORK GATEWAY ECU)

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

(b) Disconnect the J75 network gateway ECU connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J75-15 (CA5H) - J75-16 (CA5L)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

*a

Front view of wire harness connector

(to Network Gateway ECU)
OK

REPLACE NETWORK GATEWAY ECU

NG

2.

CHECK FOR OPEN IN CAN BUS LINES (COMBINATION METER ASSEMBLY)

(a) Reconnect the J75 network gateway ECU connector.

(b) Disconnect the J10 combination meter assembly connector.

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J10-29 (CANH) - J10-30 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

*a

Front view of wire harness connector

(to Combination Meter Assembly)
OK

REPLACE COMBINATION METER ASSEMBLY

NG

3.

CHECK FOR OPEN IN CAN BUS LINES (NO. 5 CAN JUNCTION CONNECTOR)

(a) Reconnect the J10 combination meter assembly connector.

(b) Disconnect the J97 No. 5 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

J97-1 (CANH) - J97-12 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Network gateway ECU

J97-6 (CANH) - J97-17 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Combination meter assembly

*a

Front view of wire harness connector

(to No. 5 CAN Junction Connector)

*b

to Network Gateway ECU

*c

to Combination Meter Assembly

Result

Proceed to

OK

A

NG (Network gateway ECU main lines)

B

NG (Combination meter assembly main lines)

C
A

REPLACE NO. 5 CAN JUNCTION CONNECTOR
B

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (NETWORK GATEWAY ECU - NO. 5 CAN JUNCTION CONNECTOR)
C

REPAIR OR REPLACE CAN MAIN BUS LINES OR CONNECTOR (COMBINATION METER ASSEMBLY - NO. 5 CAN JUNCTION CONNECTOR)
    Check Bus 5 Lines for Short Circuit
    DESCRIPTION There may be a short circuit between the bus 5 main lines and/or bus 5 branch lines when the resistance between terminals 15 (CA5H) and 16 (CA5L) of the network gateway ECU is below 54 Ω. ...

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    DESCRIPTION If an ECU or sensor is not displayed on the CAN Bus Check screen of the Techstream and some ECUs and sensors repeatedly appear and disappear from the screen when the CAN main bus lines are ...

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