Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: Open in Bus 2 Main Bus Line

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 60 km/h (37 mph) or more for 20 seconds or more. And drive the vehicle with the dynamic radar cruise control system operated for 4 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.

Check Bus 1 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 23 (CA1H) of the network gateway ECU and terminal 4 (CG) of the DLC3, or ...

Check Bus 2 Lines for Short Circuit

DESCRIPTION There may be a short circuit between the bus 2 main lines and/or bus 2 branch lines when the resistance between terminals 18 (CA4H) and 17 (CA4L) of the network gateway ECU is below 54 Ω. ...

Other materials:

Lexus RX (RX 350L, RX450h) 2016-2026 Owners Manual > Hybrid system: Hybrid system precautions
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Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Lin Communication System: Lost Communication with Power Source Control (B278C)
DESCRIPTION This DTC is stored when LIN communication between the certification ECU (smart key ECU assembly) and power management control ECU stops for 10 seconds or more. DTC No. Detection Item DTC Detection Condition Trouble Area B278C Lost Communication with Power Source Control ...