Lexus NX manuals

Lexus NX: Open in One Side of Bus 2 Branch Line

Lexus NX Service Manual / Power Source & Network / Networking / Can Communication System / Open in One Side of Bus 2 Branch Line

DESCRIPTION

When the CAN bus main lines are normal (no open, short to ground, short to +B or short between lines) and there is an ECU or sensor on the "Communication Bus Check" screen that is indicated as not communicating or whose connection status on the "Communication Bus Check" screen changes intermittently, an open in one of the wires of a CAN bus branch line is suspected.

HINT:

If there is an ECU or sensor whose connection status changes intermittently while checking the "Communication Bus Check" screen, there may be an open circuit in one of the wires of a branch line of an ECU or sensor in the bus. If an open occurs in one of the wires of a CAN branch line, it may interfere with the communication of other ECUs or sensors resulting in an incorrect state being displayed.

Symptom

Trouble Area
*1: w/ Headup Display

*2: w/ ASC System

*3: for Triple Beam Headlight

There is an ECU or sensor that is indicated as not communicating on the "Communication Bus Check" screen or whose connection status on the "Communication Bus Check" screen changes intermittently.

One side of CAN branch line is open, or output signals are incomplete.

  • Air conditioning amplifier assembly
  • Power steering ECU assembly
  • Certification ECU (smart key ECU assembly)
  • Airbag ECU assembly
  • Main body ECU (multiplex network body ECU)
  • Brake booster with master cylinder assembly (skid control ECU)
  • Steering sensor
  • Parking brake ECU assembly
  • Meter mirror sub-assembly*1
  • Stereo component equalizer assembly*2
  • Headlight ECU sub-assembly LH*3
  • Hybrid vehicle control ECU

CAUTION / NOTICE / HINT

CAUTION:

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

NOTICE:

  • 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.

    Click here

  • After performing repairs, perform the DTC check procedure and confirm that the DTCs are not output again.

    DTC check procedure: Turn the power 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 as normal.

    Click here

PROCEDURE

1.

CHECK FOR OPEN IN ONE SIDE OF BUS 2 BRANCH WIRE

(a) Based on the vehicle equipment and specifications, confirm the systems that use CAN communication.

Click here

(b) Connect the Techstream to the DLC3.

(c) Turn the power switch on (IG).

(d) Turn the Techstream on.

(e) Using the Techstream, perform "CAN Bus Check".

Click here

CAN Bus Check

(f) Observe the screen for approximately 2 minutes to check for ECUs and sensors that are displayed as not communicating.

(g) Perform the inspection as specified in the Problem Symptoms Table for the ECUs or sensors that are not communicating.

NEXT

GO TO CORRESPONDING COMMUNICATION STOP MODE

READ NEXT:

 Open in Bus 3 Main Bus Line

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

 Check Bus 3 Lines for Short Circuit

DESCRIPTION There may be a short circuit between the CAN main bus lines and/or CAN branch lines when the resistance between terminals 6 (CA3H) and 21 (CA3L) of the central gateway ECU (network gateway

 Check Bus 3 Line for Short to +B

DESCRIPTION There may be a short circuit between one of the CAN bus lines and +B when there is no resistance between terminal 6 (CA3H) of the central gateway ECU (network gateway ECU) and terminal 16

SEE MORE:

 Data List / Active Test

DATA LIST / ACTIVE TEST DATA LIST NOTICE: In the following table, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not. HINT: Using the Techstream to read the Data List allows the values or state

 System Description

SYSTEM DESCRIPTION GENERAL The windshield deicer thin heater wires are attached to the inside of the windshield glass to help deice the window surface more quickly. The indicator light illuminates while the system is operating. The system automatically turns off after approximately 15 minutes. NOTIC

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