Toyota CH-R Service Manual: Lost Communication With Headlamp Control Module "B" (U0242)

DESCRIPTION

The headlight ECU sub-assembly LH stores this DTC when the headlight ECU sub-assembly RH detects an internal malfunction or if a communication malfunction occurs between headlight ECU sub-assembly LH and headlight ECU sub-assembly RH for 10 seconds or more.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	Note
U0242	Lost Communication With Headlamp Control Module "B"	Any of the following conditions is met: Headlight ECU sub-assembly RH internal malfunction Communication malfunction occurs between headlight ECU sub-assembly LH and headlight ECU sub-assembly RH for 10 seconds or more	Headlight ECU sub-assembly LH Headlight ECU sub-assembly RH Harness or connector	-

DTC Detection Conditions:

		Vehicle Condition
		Pattern 1	Pattern 2
Diagnosis Condition	Ignition switch ON	○	○
Malfunction Status	Headlight ECU sub-assembly RH internal malfunction	○	-
	Communication malfunction occurs between headlight ECU sub-assembly LH and headlight ECU sub-assembly RH	-	○
Detection Time		-	10 seconds or more
Number of Trips		1 trip	1 trip

HINT:

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

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.

Click here

Body Electrical > HL AutoLeveling > Clear DTCs

NEXT

2.	CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Check for DTCs.

Click here

Body Electrical > HL AutoLeveling > Trouble Codes

OK:

DTC U0242 is not output.

OK

USE SIMULATION METHOD TO CHECK

NG

3.	CHECK HARNESS AND CONNECTOR (HEADLIGHT ECU SUB-ASSEMBLY LH - HEADLIGHT ECU SUB-ASSEMBLY RH)

(a) Disconnect the A16 headlight ECU sub-assembly LH connector.

(b) Disconnect the A17 headlight ECU sub-assembly RH connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
A16-20 (LINL) - A17-20 (LINL)	Always	Below 1 Ω
A16-20 (LINL) or A17-20 (LINL) - Body ground	Always	10 kΩ or higher

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.	REPLACE HEADLIGHT ECU SUB-ASSEMBLY RH

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

Click here

NEXT

5.

CLEAR DTC

(a) Clear the DTCs.

Click here

Body Electrical > HL AutoLeveling > Clear DTCs

NEXT

6.	CHECK FOR DTC

(a) Turn the ignition switch to ON.

(b) Check for DTCs.

Click here

Body Electrical > HL AutoLeveling > Trouble Codes

OK:

DTC U0242 is not output.

OK

END (HEADLIGHT ECU SUB-ASSEMBLY RH WAS DEFECTIVE)

NG

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH