DTC U0242: Lost Communication With Headlamp Control Module "B" [09/2019 - 08/2020]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / AFS / Trouble Codes.
5. Clear the DTCs.

   Body Electrical > AFS > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  2

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG)
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / AFS / Trouble Codes.
5. Check for DTCs.

   Body Electrical > AFS > Trouble Codes 

   OK

   DTC U0242 is not output.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

USE SIMULATION METHOD TO CHECK. Refer to  HOW TO PROCEED WITH TROUBLESHOOTING [09/2019 - 08/2020] 

Result: 

NG 

See step  3

1. Turn the engine switch off.
2. Disconnect the cable from the negative (-) battery terminal.
3. Disconnect the A95*1 or A16*2 headlight ECU sub-assembly LH connector.
   1. *1: for TMMT Made
   2. *2: for TMC Made
4. Measure the resistance according to the value(s) in the chart below.
   1. for TMMT Made

      Standard Resistance

      Tester Connection	Condition	Specified Condition	Result
      A95-21 (LCL) - A95-22 (LCH)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	132 Ω or more: Open circuit in main bus lines
      			Below 108 Ω: Short circuit between bus lines
      A95-21 (LCL) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: LCL short to ground
      A95-22 (LCH) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: LCH short to ground
      A95-21 (LCL) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: LCL +B short
      A95-22 (LCH) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: LCH +B short

   2. for TMC Made

      Standard Resistance

      Tester Connection	Condition	Specified Condition	Result
      A16-21 (LCL) - A16-22 (LCH)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω	132 Ω or more: Open circuit in main bus lines
      			Below 108 Ω: Short circuit between bus lines
      A16-21 (LCL) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: LCL short to ground
      A16-22 (LCH) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher	Below 200 Ω: LCH short to ground
      A16-21 (LCL) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: LCL +B short
      A16-22 (LCH) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher	Below 6 kΩ: LCH +B short

   Result

   Result	Proceed to
   OK	A
   NG (Open circuit in main lines)	B
   NG (Short circuit between main lines)	C
   NG (Short to +B or ground)	D

Result: 

A 

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [09/2019 - 08/2020] 

Result: 

C 

See step  5

Result: 

D 

See step  6

Result: 

B 

See step  4

1. Connect the A95*1 or A16*2 headlight ECU sub-assembly LH connector.
   1. *1: for TMMT Made
   2. *2: for TMC Made
2. Disconnect the A17 headlight ECU sub-assembly RH connector.
3. Measure the resistance according to the value(s) in the chart below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A17-21 (LCL) - A17-22 (LCH)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  7

Result: 

NG 

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR 

1. Connect the A95*1 or A16*2 headlight ECU sub-assembly LH connector.
   1. *1: for TMMT Made
   2. *2: for TMC Made
2. Disconnect the A17 headlight ECU sub-assembly RH connector.
3. Measure the resistance according to the value(s) in the chart below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A17-21 (LCL) - A17-22 (LCH)	Cable disconnected from negative (-) battery terminal	108 to 132 Ω

   Result

   Proceed to
   OK
   NG

Result: 

OK 

See step  7

Result: 

NG 

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR 

1. Disconnect the A17 headlight ECU sub-assembly RH connector.
2. Measure the resistance according to the value(s) in the chart below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A17-21 (LCL) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher
   A17-22 (LCH) - GND	Cable disconnected from negative (-) battery terminal	200 Ω or higher
   A17-21 (LCL) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher
   A17-22 (LCH) - +B	Cable disconnected from negative (-) battery terminal	6 kΩ or higher

   Result

   Proceed to
   OK
   NG

Result: 

NG 

REPAIR OR REPLACE CAN BUS MAIN LINE OR CONNECTOR 

Result: 

OK 

See step  7

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

   Refer to REMOVAL [09/2019 - 08/2020]

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  8

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / AFS / Trouble Codes.
5. Clear the DTCs.

   Body Electrical > AFS > Clear DTCs 

   Result

   Proceed to
   NEXT

Result: 

NEXT 

See step  9

1. Connect the Techstream to the DLC3.
2. Turn the engine switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / AFS / Trouble Codes.
5. Check for DTCs.

   Body Electrical > AFS > Trouble Codes 

   OK

   DTC U0242 is not output.

   Result

   Proceed to
   OK
   NG

Result: 

OK 

END (HEADLIGHT ECU SUB-ASSEMBLY RH WAS DEFECTIVE) 

Result: 

NG 

REPLACE HEADLIGHT ECU SUB-ASSEMBLY LH. Refer to  REMOVAL [09/2019 - 08/2020]