DTC B2443: Lost Communication with Left Headlight and Right Headlight LIN [09/2014 - 10/2018]: Procedure

WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2018 Lexus RC 350, 2018 Lexus RC 300, 2017 Lexus RC 350, 2017 Lexus RC 300, and 2017 Lexus RC 200t. However, it is still accessible from the selected car via links, so may be relevant.

CLEAR DTC

Clear the DTCs.

Refer to DTC CHECK / CLEAR [09/2014 - 10/2018]

Body Electrical > HL AutoLeveling > Clear DTCs

Result

Proceed to
NEXT

Result:

See step 2

CHECK FOR DTC

Turn the engine switch on (IG).

Check for DTCs.

Refer to DTC CHECK / CLEAR [09/2014 - 10/2018]

Body Electrical > HL AutoLeveling > Trouble Codes

DTC B2443 is not output.

Result

Proceed to
OK
NG

Result:

USE SIMULATION METHOD TO CHECK. Refer to HOW TO PROCEED WITH TROUBLESHOOTING [09/2014 - 10/2015] , or refer to HOW TO PROCEED WITH TROUBLESHOOTING [10/2015 - 11/2017] , or refer to HOW TO PROCEED WITH TROUBLESHOOTING [11/2017 - 10/2018]

Result:

See step 3

CHECK HARNESS AND CONNECTOR (HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY LH - HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY RH)

Disconnect the A36 Headlight light control ECU sub-assembly LH connector.
Disconnect the A7 Headlight light control ECU sub-assembly RH connector.

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

Standard Resistance

Tester Connection	Condition	Specified Condition
A36-20 (LINL) - A7-20 (LINL)	Always	Below 1 Ω
A36-20 (LINL) - Body ground	Always	10 kΩ or higher

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR

Result:

See step 4

REPLACE HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY RH

Replace the headlight light control ECU sub-assembly RH with a new or known good one.

Refer to REMOVAL [09/2014 - 10/2018]

Result

Proceed to
NEXT

Result:

See step 5

CLEAR DTC

Clear the DTCs.

Refer to DTC CHECK / CLEAR [09/2014 - 10/2018]

Body Electrical > HL AutoLeveling > Clear DTCs

Result

Proceed to
NEXT

Result:

See step 6

CHECK FOR DTC

Turn the engine switch on (IG).

Check for DTCs.

Refer to DTC CHECK / CLEAR [09/2014 - 10/2018]

Body Electrical > HL AutoLeveling > Trouble Codes

DTC B2443 is not output.

Result

Proceed to
OK
NG

Result:

END (HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY RH WAS DEFECTIVE)

Result:

REPLACE HEADLIGHT LIGHT CONTROL ECU SUB-ASSEMBLY LH. Refer to REMOVAL [09/2014 - 10/2018]