Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual: Lost Communication with Wiper ECU LIN (B1245)

Lexus RX (RX 350L, RX450h) 2016-2025 Repair Manual / Vehicle Exterior / Wiper / Washer / Wiper And Washer System / Lost Communication with Wiper ECU LIN (B1245)

DESCRIPTION

The main body ECU (multiplex network body ECU) and windshield wiper motor and link assembly communicate via LIN communication. The main body ECU (multiplex network body ECU) stores this DTC if communication becomes abnormal.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Memory

DTC Output from

B1245

Lost Communication with Wiper ECU LIN

When the battery voltage is 9.5 V or more, a communication malfunction between the main body ECU (multiplex network body ECU) and windshield wiper motor and link assembly (wiper ECU) is detected for 10 seconds or more
  • Front wiper motor and link assembly
  • Harness or connector
  • Main body ECU (multiplex network body ECU)

○

Main body ECU (multiplex network body ECU)

WIRING DIAGRAM

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > Main Body > Clear DTCs
NEXT

2.

CHECK FOR DTC

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

(b) Check for DTCs.

Click here

Body Electrical > Main Body > Trouble Codes

Result

Proceed to

DTC B1245 is not output.

A

DTC B1245 is output.

B
A

USE SIMULATION METHOD TO CHECK

B

3.

CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) - FRONT WIPER MOTOR AND LINK ASSEMBLY)

(a) Disconnect the J9 main body ECU (multiplex network body ECU) connector.

(b) Disconnect the i1 front wiper motor and link assembly connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

J9-8 (LIN3) - i1-2 (MPX1)

Always

Below 1 Ω

J9-8 (LIN3) or i1-2 (MPX1) - Body ground

Always

10 kΩ or higher
NG

GO TO STEP 9

OK

4.

CHECK HARNESS AND CONNECTOR (FRONT WIPER MOTOR AND LINK ASSEMBLY - POWER SOURCE)

(a) Measure the voltage according to the value(s) in the table below.

Standard Voltage:

Tester Connection

Condition

Specified Condition

i1-3 (L) - Body ground

Engine switch off

Below 1 V

Engine switch on (IG)

11 to 14 V
NG

GO TO STEP 8

OK

5.

CHECK HARNESS AND CONNECTOR (FRONT WIPER MOTOR AND LINK ASSEMBLY - BODY GROUND)

(a) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

i1-4 (+S) - Body ground

Always

Below 1 Ω
NG

GO TO STEP 7

OK

6.

REPLACE FRONT WIPER MOTOR AND LINK ASSEMBLY

(a) Replace the front wiper motor and link assembly with a new or known good one.

Click here

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

(c) Check for DTCs.

Click here

Body Electrical > Main Body > Trouble Codes

Result

Proceed to

DTC B1245 is not output.

A

DTC B1245 is output.

B
A

END
B

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

7.

CHECK WIPER MOTOR WIRE

(a) Remove the wiper motor wire.

Click here

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

i1-4 (+S) - iA1-3

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Front Wiper Motor and Link Assembly)

*b

Front view of wire harness connector

(to Wire Harness)
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

REPLACE WIPER MOTOR WIRE

8.

CHECK WIPER MOTOR WIRE

(a) Remove the wiper motor wire.

Click here

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

i1-3 (L) - iA1-2

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Front Wiper Motor and Link Assembly)

*b

Front view of wire harness connector

(to Wire Harness)
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

REPLACE WIPER MOTOR WIRE

9.

CHECK WIPER MOTOR WIRE

(a) Remove the wiper motor wire.

Click here

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

i1-2 (MPX1) - iA1-1

Always

Below 1 Ω

*a

Front view of wire harness connector

(to Front Wiper Motor and Link Assembly)

*b

Front view of wire harness connector

(to Wire Harness)
OK

REPAIR OR REPLACE HARNESS OR CONNECTOR
NG

REPLACE WIPER MOTOR WIRE

    Diagnostic Trouble Code Chart
    DIAGNOSTIC TROUBLE CODE CHART Wiper and Washer System DTC No. Detection Item DTC Detection Condition Link B1245 Lost Communication with Wiper ECU LIN When the battery voltage is 9.5 V ...

    Lost Communication with Combination Switch ECU (B1278)
    DESCRIPTION The main body ECU (multiplex network body ECU) and windshield wiper switch assembly communicate via LIN communication. The main body ECU (multiplex network body ECU) stores this DTC if com ...

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