Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual: ECM Communication (C124A00)

Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual / Brake / Brake Control / Dynamic Control Systems / Vehicle Stability Control System / ECM Communication (C124A00)

DESCRIPTION

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

C124A00

ECM Communication

Any of the following is detected:

  • The engine type, powertrain variation, engine stop and start ECU availability and destination information sent from the ECM do not match the information stored in the skid control ECU (brake actuator assembly).
  • No system information stored in the skid control ECU (brake actuator assembly).
  • When the skid control ECU (brake actuator assembly) is malfunctioning.
  • Incorrect ECM installed
  • Skid control ECU (Brake actuator assembly)
DTC Detection Conditions: C124A00
 

Vehicle Condition

Pattern 1

Pattern 2

Pattern 3

Diagnosis Condition

-

-

-

-

Malfunction Status

The engine type, powertrain variation, engine stop and start ECU availability and destination information sent from the ECM do not match the information stored in the skid control ECU (brake actuator assembly)

○

-

-

No system information stored in the skid control ECU (brake actuator assembly)

-

○

-

When the skid control ECU (brake actuator assembly) is malfunctioning

-

-

○

Detection Time

-

-

-

Number of Trips

1 trip

1 trip

1 trip

HINT:

DTC will be output when conditions for any of the patterns in the table above are met.

CAUTION / NOTICE / HINT

NOTICE:

  • After replacing the skid control ECU (brake actuator assembly), perform "Calibration".

    Click here

  • Before replacing the ECM, refer to Registration.

    Click here

PROCEDURE

1.

CHECK PART NUMBER (ECM)

(a) Check that the proper ECM is installed.

OK:

Proper ECM is installed.

(b) Check if the ECM was replaced before the DTC was stored.

OK:

ECM was not replaced

Result

Proceed to

OK

A

NG (A proper ECM is not installed and/or the ECM was replaced.)

B
B

REPLACE ECM

A

2.

CHECK PART NUMBER (BRAKE ACTUATOR ASSEMBLY)

(a) Check that the proper brake actuator assembly is installed.

OK:

Proper brake actuator assembly is installed.

(b) Check if the brake actuator assembly was replaced before the DTC was recorded.

OK:

The brake actuator assembly was not replaced.

Result

Proceed to

OK

A

NG (The brake actuator assembly was replaced.)

B

NG (A proper brake actuator assembly is not installed.)

C
C

GO TO STEP 5

B

REPLACE BRAKE ACTUATOR ASSEMBLY

A

3.

CLEAR DTC

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(c) Operate the Techstream to clear the codes. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Clear DTCs

(d) Press the DTC clear button.

(e) Turn the engine switch off.

NEXT

4.

RECONFIRM DTC

(a) Turn the engine switch on (IG).

(b) Read the DTCs following the prompts on the Techstream. Enter the following menus: Chassis / Brake/EPB / Trouble Codes.

Chassis > Brake/EPB > Trouble Codes

(c) Check if the same DTC is output.

Result

Proceed to

DTC C124A00 is not output.

A

DTC C124A00 is output.

B
A

USE SIMULATION METHOD TO CHECK

B

REPLACE BRAKE ACTUATOR ASSEMBLY

5.

CHECK CALIBRATION

(a) After replacing the skid control ECU (brake actuator assembly), check that "Calibration" is performed.

HINT:

If a new skid control ECU (brake actuator assembly) was installed, C121054 and C051D54 are output before "Calibration" is performed.

Result

Proceed to

Calibration performed

A

Calibration not performed

B
A

REPLACE BRAKE ACTUATOR ASSEMBLY

B

PERFORM CALIBRATION

    Yaw Rate Sensor / Multi-axis Acceleration Sensor Module "A" (C124000)
    DESCRIPTION If the identification ID of the yaw rate and acceleration sensor is different to that stored in the skid control ECU (brake actuator assembly), this DTC is stored. DTC No. Detection I ...

    Yaw Rate Sensor Signal Compare Failure (C124F62)
    DESCRIPTION for Optitron Meter Type: This DTC is stored when the skid control ECU (brake actuator assembly) detects improper installation of the yaw rate sensor (airbag sensor assembly) or an abnor ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Audio And Visual System (for 12.3 Inch Display): Extension Module Malfunction 2 (B1556)
    DESCRIPTION This DTC is stored when a malfunction occurs in the Navigation ECU. DTC No. Detection Item DTC Detection Condition Trouble Area B1556 Extension Module Malfunction 2 When any of the following conditions is met: Internal power supply malfunction Internal hard drive ma ...

    Lexus RX (RX 350L, RX450h) 2016-2026 Repair Manual > Oil Pan And Oil Level Sensor: Inspection
    INSPECTION PROCEDURE 1. INSPECT ENGINE OIL LEVEL SENSOR (a) Measure the resistance according to the value(s) in the table below. Standard Resistance: Tester Connection Condition Specified Condition 1 - Body ground ON Below 1 Ω OFF 10 kΩ or higher If the result is not as ...

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Owners Manual

    Lexus RX (RX 350L, RX450h) 2016-{YEAR} Repair Manual

    © 2026 Copyright www.lexusrx.net
    0.0102