Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Assist Map Number Un-Writing (C1581)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Steering / Power Assist Systems / Power Steering System / Assist Map Number Un-Writing (C1581)

DESCRIPTION

This DTC will be stored if the power steering ECU assembly determines that the assist map is not written in the ECU.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Return-to-normal Condition

Note

C1581

Assist Map Number Un-Writing

Assist map not written in power steering ECU assembly
  • CAN communication system
  • ECM
  • Main body ECU (Multiplex network body ECU)
  • Skid control ECU (Brake actuator assembly)
  • Power steering ECU assembly

EPS warning light: Comes on

Assist Map Writing is performed or the power switch is turned on (IG) again

-

CAUTION / NOTICE / HINT

NOTICE:

If the power steering ECU assembly has been replaced, perform assist map writing and torque sensor zero point calibration.

Click here

HINT:

Related parts store information necessary for assist map writing.

Related Part:

  • ECM
  • Main body ECU (Multiplex network body ECU)
  • Skid control ECU (Brake actuator assembly)

PROCEDURE

1.

PERFORM ASSIST MAP WRITING

(a) Perform assist map writing.

Click here

Chassis > EMPS > Utility

Tester Display

Signal Check

(b) Check for DTCs.

Click here

Chassis > EMPS > Trouble Codes

Result

Proceed to

DTC C1581 is output.

A

DTC C1581 is not output.

B

NOTICE:

DTC C1581 is cleared after the assist map is written.

B

END
A

2.

CHECK CAN COMMUNICATION SYSTEM

(a) Check for DTCs.

Click here

Result

Proceed to

CAN communication system DTCs are not output.

A

CAN communication system DTCs are output.

B
B

GO TO CAN COMMUNICATION SYSTEM

A

3.

CHECK RELATED PART

(a) Confirm if the related part has the correct part number.

Related Part

ECM

Main body ECU (Multiplex network body ECU)

Skid control ECU (Brake actuator assembly)

NOTICE:

When removing the related part to check it, be sure to follow the appropriate procedures and precautions.

  • ECM

    Click here

  • Main body ECU (Multiplex network body ECU)

    Click here

  • Skid control ECU (Brake actuator assembly)

    Click here

Result

Proceed to

The related part has the correct part number.

A

The related part has an incorrect part number.

B
B

GO TO STEP 5

A

4.

CHECK FOR DTC

(a) Select Health Check on the Techstream screen and check if system DTCs of the related part are output.

HINT:

If system DTCs of the related part are stored, assist map writing to the power steering ECU assembly may not be performed properly.

Result

Proceed to

System DTCs of the related part are output.

A

System DTCs of the related part are not output.

B
A

REPAIR CIRCUIT INDICATED BY OUTPUT CODE
B

REPLACE POWER STEERING ECU ASSEMBLY

5.

REPLACE RELATED PART WITH PART THAT HAS CORRECT PART NUMBER

(a) Replace the related part with one that has the correct part number.

  • ECM

    Click here

  • Main body ECU (Multiplex network body ECU)

    Click here

  • Skid control ECU (Brake actuator assembly)

    Click here

NEXT

6.

CHECK FOR DTC

(a) Check for DTCs.

Click here

Chassis > EMPS > Trouble Codes

Result

Proceed to

DTCs are not output.

A

DTCs are output.

B
A

END
B

REPLACE POWER STEERING ECU ASSEMBLY

    Error in Matching of ECUs (C1567)
    DESCRIPTION Based on the steering sensor signal, the power steering ECU assembly determines if the correct type of steering sensor is installed. DTC No. Detection Item DTC Detection Condition ...

    Assist Map Number Mismatch (C1582)
    DESCRIPTION When an incorrect ECM, main body ECU (multiplex network body ECU) or skid control ECU (brake actuator assembly) is installed after the assist map has been written to the power steering ECU ...

    Other materials:

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Meter / Gauge System: Lost Communication with EMV (B1321)
    DESCRIPTION After the combination meter assembly has started, the combination meter assembly attempts to detect the radio receiver assembly by performing communication via local bus. This DTC is stored when the radio receiver assembly has been detected but communication between the combination meter ...

    Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual > Smart Access System With Push-button Start (for Start Function): Detecting Vehicle Submersion (B2277)
    DESCRIPTION This DTC is stored when a malfunction in the water submersion detection circuit inside the certification ECU (smart key ECU assembly) is detected. DTC No. Detection Item DTC Detection Condition Trouble Area Note B2277 Detecting Vehicle Submersion Water submersion detec ...

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

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

    © 2025 Copyright www.lexusrx.net
    0.0104