Lexus NX manuals

Lexus NX: Control Module Communication Bus OFF (U0073,U0120,U0123,U0124,U0126,U0128,U0293)

Lexus NX Service Manual / Brake / Brake Control / Dynamic Control Systems / Electronically Controlled Brake System / Control Module Communication Bus OFF (U0073,U0120,U0123,U0124,U0126,U0128,U0293)

DESCRIPTION

The skid control ECU (brake booster with master cylinder assembly) receives signals from the hybrid vehicle control ECU, steering sensor, parking brake ECU assembly, certification ECU (smart key ECU assembly) and yaw rate and acceleration sensor (airbag ECU assembly) via CAN communication.

DTC No.

Detection Item

INF Code

DTC Detection Condition

Trouble Area

Note

U0073

Control Module Communication Bus OFF

461

462

463

464

465

466
  • INF Code: 461
    • Either of the following is detected:
      1. Yaw rate and acceleration sensor communication is disabled for 1 second or more.
      2. Yaw rate and acceleration sensor communication is disabled once or more per 5 seconds 10 times or more within 60 seconds.
  • INF Code: 462
    • Either of the following is detected:
      1. Steering sensor communication is disabled for 1 second or more.
      2. Steering sensor communication is disabled once or more per 5 seconds 10 times or more within 60 seconds.
  • INF Code: 463, 464
    • Bus off occurs once or more per 0.1 seconds 10 times repeatedly.
  • INF Code: 465, 466
    • Sending does not complete within 5 seconds after data is output from the skid control ECU (brake booster with master cylinder assembly).
  • INF Code: 461
    • CAN communication line (V bus)
    • Yaw rate and acceleration sensor (Airbag ECU assembly)
    • Skid control ECU (Brake booster with master cylinder assembly)
  • INF Code: 462
    • CAN communication line (V bus)
    • Steering sensor
    • Skid control ECU (Brake booster with master cylinder assembly)
  • INF Code: 463, 464, 465, 466
    • CAN communication line
    • Skid control ECU (Brake booster with master cylinder assembly)

-

U0120

Lost Communication With Starter / Generator Control Module

471

Push start switch data is invalid for 3 seconds or more.
  • CAN communication line (V bus)
  • Certification ECU (Smart key ECU assembly)
  • Skid control ECU (Brake booster with master cylinder assembly)

-

U0123

Lost Communication With Yaw Rate Sensor Module

731

732
  • INF Code: 731
    • Yaw rate sensor communication is disabled for 1 second or more.
  • INF Code: 732
    • Yaw rate sensor communication is disabled once or more per 5 seconds 10 times or more within 60 seconds.
  • CAN communication line (V bus)
  • Yaw rate sensor (Airbag ECU assembly)
  • Skid control ECU (Brake booster with master cylinder assembly)

-

U0124

Lost Communication With Lateral Acceleration Sensor Module

591

592
  • INF Code: 591
    • Acceleration sensor communication is disabled for 1 second or more.
  • INF Code: 592
    • Acceleration sensor communication is disabled once per 5 seconds 10 times or more within 60 seconds.
  • CAN communication line (V bus)
  • Acceleration sensor (Airbag ECU assembly)
  • Skid control ECU (Brake booster with master cylinder assembly)

-

U0126

Lost Communication With Steering Angle Sensor Module

741

742
  • INF Code: 741
    • Steering sensor communication is disabled for 1 second or more.
  • INF Code: 742
    • Steering sensor communication is disabled once or more per 5 seconds 10 times or more within 60 seconds.
  • CAN communication line (V bus)
  • Steering sensor
  • Skid control ECU (Brake booster with master cylinder assembly)

-

U0128

Lost Communication With EPB Module

425

With terminal IG1 voltage at 10 V or more, data cannot be received from the electric parking brake ECU for 1 second.
  • CAN communication line (V bus)
  • Parking brake ECU assembly
  • Skid control ECU (Brake booster with master cylinder assembly)

EPB: Electric parking brake system

U0293

Lost Communication With Hybrid Vehicle Control System

411

412

413

Either of the following is detected:

  • When terminal IG2 voltage is 9.5 V or more, data from the hybrid vehicle control ECU cannot be received for 2 seconds or more.
  • When terminal IG2 voltage is 9.5 V or more, data from the hybrid vehicle control ECU cannot be received once or more within 5 seconds occur 10 times in succession.
  • CAN communication line (V bus)
  • Hybrid vehicle control ECU
  • Skid control ECU (Brake booster with master cylinder assembly)

-

WIRING DIAGRAM

Click here

PROCEDURE

1.

CHECK HARNESS AND CONNECTOR (MOMENTARY INTERRUPTION)

(a) Using the Techstream, check for any momentary interruptions in the wire harness and connector corresponding to a DTC.

Click here

Chassis > ABS/VSC/TRAC > Data List

Tester Display

Measurement Item

Range

Normal Condition

Diagnostic Note

Yaw Rate Open

Yaw rate sensor open detection

Error or Normal

Normal: Normal

Error: Momentary interruption

Deceleration Open

Acceleration sensor open detection

Error or Normal

Normal: Normal

Error: Momentary interruption

Steering Open

Steering sensor open detection

Error or Normal

Normal: Normal

Error: Momentary interruption

HV Communication Open

Hybrid vehicle communication open detection

Error or Normal

Normal: Normal

Error: Momentary interruption
Chassis > ABS/VSC/TRAC > Data List

Tester Display

Yaw Rate Open

Deceleration Open

Steering Open

HV Communication Open

Result

Proceed to

There is a constant open circuit.

A

There are no momentary interruptions.

B

There are momentary interruptions.

C

HINT:

Perform the above inspection before disconnecting any sensors or connectors.

B

GO TO STEP 3

C

GO TO STEP 4

A

2.

CHECK IF EACH CONNECTOR IS SECURELY CONNECTED (HYBRID VEHICLE CONTROL ECU, SENSOR)

(a) Turn the power switch off.

(b) Check if each sensor and ECU connector is securely connected.

OK:

Each sensor and ECU connector is securely connected.

NG

CONNECT CONNECTOR TO EACH SENSOR OR ECU CORRECTLY
OK

3.

RECONFIRM DTC

(a) Turn the power switch off.

(b) Record the output DTCs (for the ABS, VSC, electronically controlled brake system and/or CAN communication system).

for the ABS, VSC and Electronically Controlled Brake System: Click here

for the CAN Communication System: Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

HINT:

If CAN communication system DTCs and relevant sensor DTCs are output simultaneously, troubleshoot the relevant sensor DTCs (for the ABS, VSC and/or electronically controlled brake system) after the CAN communication system returns to normal.

Result

Proceed to

DTCs are not output.

A

ABS, VSC and/or electronically controlled brake system DTCs are output.

B

CAN communication system DTCs are output.

C
A

USE SIMULATION METHOD TO CHECK

B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

C

INSPECT CAN COMMUNICATION SYSTEM

4.

REPAIR OR REPLACE HARNESS OR CONNECTOR

(a) Turn the power switch off.

(b) Repair or replace the harness or connector.

(c) Check for any momentary interruptions between the skid control ECU (brake booster with master cylinder assembly) and each sensor or ECU.

Click here

NEXT

5.

RECONFIRM DTC

(a) Turn the power switch off.

(b) Clear the DTCs.

Click here

Chassis > ABS/VSC/TRAC > Clear DTCs

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

(d) Drive the vehicle at a speed of 15 km/h (9 mph) or more and turn the steering wheel to the right and left.

(e) Check that no CAN communication system DTCs are output.

Click here

(f) If ABS, VSC and/or electronically controlled brake system DTCs are output, record them.

Click here

Chassis > ABS/VSC/TRAC > Trouble Codes

Result

Proceed to

DTCs are not output.

A

ABS, VSC and/or electronically controlled brake system DTCs are output.

B

CAN communication system DTCs are output.

C

HINT:

The CAN communication system must be normal when performing troubleshooting for sensor DTCs (for the ABS, VSC and/or electronically controlled brake system).

A

END
B

REPAIR CIRCUITS INDICATED BY OUTPUT DTCS

C

INSPECT CAN COMMUNICATION SYSTEM

READ NEXT:

 ABS Warning Light Remains ON

DESCRIPTION The skid control ECU (brake booster with master cylinder assembly) is connected to the combination meter assembly via CAN communication. If any of the following is detected, the ABS warnin

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 Brake Warning Light Remains ON

DESCRIPTION The skid control ECU (brake booster with master cylinder assembly) is connected to the combination meter assembly via CAN communication. If any of the following is detected, the brake warn

SEE MORE:

 Diagnostic Trouble Code Chart

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