Light Control Switch Circuit: Wiring Diagram

1. Check the DATA LIST for the proper functioning of the combination switch.

   Main body ECU 

   MAIN BODY ECU DATA LIST
   
   

   Item	Measurement Item / Display (Range)	Normal Condition	Diagnostic Note
   DIMMER SW	Headlight dimmer switch signal / ON or OFF	ON: Headlight dimmer switch is in HIGH or FLASH position OFF: Headlight dimmer switch is in LOW position	-
   HIGH FLASHER SW	Headlight dimmer switch signal / ON or OFF	ON: Headlight dimmer switch is in FLASH position OFF: Headlight dimmer switch is in except FLASH position	-
   AUTO LIGHT SW	Auto light switch signal / ON or OFF	ON: Light control switch is in AUTO position OFF: Light control switch is in except AUTO position	-
   HEAD LIGHT SW	Headlight control switch signal / ON or OFF	ON: Light control switch is in HEAD position OFF: Light control switch is in except HEAD position	-
   TAIL LIGHT SW	Taillight switch signal / ON or OFF	ON: Light control switch is in TAIL or HEAD position OFF: Light control switch is not in TAIL or HEAD position	-

OK : PROCEED TO NEXT INSPECTION PROCEDURE SHOWN IN  PROBLEM SYMPTOMS TABLE  

NG : GO TO NEXT STEP 

Fig 2: Identifying 1L, B5 And B7 Connectors

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Disconnect the 1I junction block connector.
2. Disconnect the B5 and B7 ECU connectors.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   TESTER CONNECTION - SPECIFIED CONDITION
   
   

   Tester Connection	Condition	Specified Condition
   1I-4 (HU) - Body ground	Headlight dimmer switch LOW	10 k or higher
   	Headlight dimmer switch HIGH	Below 1
   B5-13 (LIB1) - Body ground	Fog switch OFF	10 k or higher
   	Fog switch AUTO	Below 1
   B5-18 (AUTO) - Body ground	Light control switch OFF	10 k or higher
   	Light control switch AUTO	Below 1
   B7-3 (HEAD) - Body ground	Light control switch OFF	10 k or higher
   	Light control switch HEAD	Below 1
   B7-21 (TAIL) - Body ground	Light control switch OFF	10 k or higher
   	Light control switch TAIL	Below 1
   B7-22 (HF) - Body ground	Headlight dimmer switch LOW	10 k or higher
   	Headlight dimmer switch FLASH	Below 1

OK : PROCEED TO NEXT INSPECTION PROCEDURE SHOWN IN  PROBLEM SYMPTOMS TABLE  

NG : GO TO NEXT STEP 

1. Inspect light control switch.
   1. Measure the resistance of the switch.

      Standard resistance 

      LIGHT CONTROL SWITCH STANDARD RESISTANCE
      
      

      Tester Connection	Switch Condition	Specified Condition
      12 (EL) - 18 (T) 12 (EL) - 19 (A) 12 (EL) - 20 (H)	OFF	10 k or higher
      12 (EL) - 18 (T)	TAIL	Below 1
      12 (EL) - 18 (T) 12 (EL) - 20 (H)	HEAD
      12 (EL) - 19 (A)	AUTO

      Fig 3: Inspecting Combination Switch

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Inspect headlight dimmer switch.
   1. Measure the resistance of the switch.

      Standard resistance 

      HEADLIGHT DIMMER SWITCH RESISTANCE
      
      

      Tester Connection	Switch Condition	Specified Condition
      11 (HU) - 12 (EL) 12 (EL) - 17 (HF)	FLASH	Below 1
      12 (EL) - 16 (HL)	Low
      11 (HU) - 12 (EL)	High

3. Inspect fog switch.
   1. Measure the resistance of the switch.

      Standard resistance 

      FOG SWITCH RESISTANCE
      
      

      Tester Connection	Switch Condition	Specified Condition
      4 (BFG) - 3 (LFG)	ON	Below 1
      	OFF	10 k or higher

NG : REPLACE COMBINATION SWITCH 

OK : REPAIR OR REPLACE HARNESS AND CONNECTOR