Toyota Corolla Cross Owners & Service Manuals

Toyota Corolla Cross: Headlight Source LH Malfunction (B243900,B243A00)

Toyota Corolla Cross (2022-2024) Service Manual / Vehicle Exterior / Lighting (ext) / Lighting System (w/ Afs) / Headlight Source LH Malfunction (B243900,B243A00)

DESCRIPTION

The headlight ECU sub-assembly LH and headlight ECU sub-assembly RH internally boost the power supply voltage to ensure a constant supplied current for the Lo/Hi beam LED of their respective headlight.

By monitoring the LED power supply voltage, abnormal current and malfunctions can be detected.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

B243900

Headlight Source LH Malfunction

 Detection condition:
  • All of the following conditions are met:
    • Ignition switch ON
    • Low beam headlights on
Malfunction status:
  • Headlight assembly malfunction
  • Open/short in Lo/Hi beam circuit
Malfunction duration:
  • 10 seconds or more
  • Headlight unit assembly LH
  • Headlight ECU sub-assembly LH

B243A00

Headlight Source RH Malfunction

 Detection condition:
  • All of the following conditions are met:
    • Ignition switch ON
    • Low beam headlights on
Malfunction status:
  • Headlight assembly malfunction
  • Open/short in Lo/Hi beam circuit
Malfunction duration:
  • 10 seconds or more
  • Headlight unit assembly RH
  • Headlight ECU sub-assembly RH

WIRING DIAGRAM

CAUTION / NOTICE / HINT

NOTICE:

If the headlight ECU sub-assembly LH has been replaced, it is necessary to synchronize the vehicle information and initialize the headlight ECU sub-assembly LH.

Click here

PROCEDURE

1.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Headlight Control > Clear DTCs Body Electrical > Headlight Control (Sub) > Clear DTCs
NEXT

2.

CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Operate the light control switch to turn on the low beam headlights and wait 10 seconds or more.

(c) Check for DTCs.

Body Electrical > Headlight Control > Trouble Codes Body Electrical > Headlight Control (Sub) > Trouble Codes

OK:

DTC B243900 and B243A00 are not output.

Result

Proceed to

DTCs are not output

A

B243900 is output

B

DTC B243A00 is output

C
A

USE SIMULATION METHOD TO CHECK

C

GO TO STEP 6

B

3.

CHECK HEADLIGHT UNIT ASSEMBLY LH

(a) Interchange the headlight unit assembly LH with RH and connect the connectors.

Click here

NEXT

4.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Headlight Control > Clear DTCs Body Electrical > Headlight Control (Sub) > Clear DTCs
NEXT

5.

CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Operate the light control switch to turn on the low beam headlights and wait 10 seconds or more.

(c) Check for DTCs.

Body Electrical > Headlight Control > Trouble Codes Body Electrical > Headlight Control (Sub) > Trouble Codes

Result

Proceed to

B243900 is output

A

B243A00 is output

B
A

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH

B

REPLACE HEADLIGHT UNIT ASSEMBLY LH

6.

CHECK HEADLIGHT UNIT ASSEMBLY RH

(a) Interchange the headlight unit assembly RH with LH and connect the connectors.

Click here

NEXT

7.

CLEAR DTC

(a) Clear the DTCs.

Body Electrical > Headlight Control > Clear DTCs Body Electrical > Headlight Control (Sub) > Clear DTCs
NEXT

8.

CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Operate the light control switch to turn on the low beam headlights and wait 10 seconds or more.

(c) Check for DTCs.

Body Electrical > Headlight Control > Trouble Codes Body Electrical > Headlight Control (Sub) > Trouble Codes

Result

Proceed to

B243A00 is output

A

B243900 is output

B
A

REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH

B

REPLACE HEADLIGHT UNIT ASSEMBLY RH

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