Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Open in Bus 3 Main Bus Line

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Power Source & Network / Networking / Can Communication System / Open in Bus 3 Main Bus Line

DESCRIPTION

There may be an open circuit in one of the bus 3 main lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the network gateway ECU is 70 Ω or higher.

Symptom

Trouble Area

Resistance between terminals 6 (CA3H) and 21 (CA3L) of network gateway ECU is 70 Ω or higher.
  • CAN main bus line or connector
  • Network gateway ECU
  • No. 6 CAN junction connector

This malfunction is not related to the lines of a bus 3 branch or to ECUs or sensors connected to a bus 3 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: Turn the engine switch on (IG) and wait for at least 31 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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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. 6 CAN JUNCTION CONNECTOR)

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

(b) Disconnect the J98 No. 6 CAN junction connector.

*a

Front view of wire harness connector

(to No. 6 CAN Junction Connector)

*b

to Network Gateway ECU

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

Connected to

J98-7 (CANH) - J98-18 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Network gateway ECU

J98-11 (CANH) - J98-22 (CANL)

Cable disconnected from negative (-) battery terminal

108 to 132 Ω

Network gateway ECU
OK

REPLACE NO. 6 CAN JUNCTION CONNECTOR
NG

2.

CHECK FOR OPEN IN CAN BUS LINES (NETWORK GATEWAY ECU - NO. 6 CAN JUNCTION CONNECTOR)

(a) Reconnect the J98 No. 6 CAN junction connector.

(b) Disconnect the J75 network gateway ECU connector.

*a

Front view of wire harness connector

(to Network Gateway ECU)

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

Standard Resistance:

Tester Connection

Condition

Specified Condition

J75-6 (CA3H) - J75-19 (CAYH)

Cable disconnected from negative (-) battery terminal

Below 1 Ω

J75-21 (CA3L) - J75-20 (CAYL)

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. 6 CAN JUNCTION CONNECTOR)
    Check Bus 2 Line for Short to GND
    DESCRIPTION There may be a short circuit between one of the CAN bus lines and GND when there is no resistance between terminal 18 (CA4H) of the network gateway ECU and terminal 4 (CG) of the DLC3, or ...

    Check Bus 3 Lines for Short Circuit
    DESCRIPTION There may be a short circuit between the bus 3 main lines and/or bus 3 branch lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the network gateway ECU is below 54 Ω. ...

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