Light Control Switch Circuit: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the tester on.
4. Enter the following menus: Body Electrical / Body / Data List /
5. According to the display on tester, read the "Data List".

   Body (Main Body ECU)

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   High Flasher SW	Passing light switch signal / ON or OFF	ON: Headlight dimmer switch is in FLASH (PASS) position OFF: Headlight dimmer switch is not in FLASH (PASS) position	-
   Dimmer SW	Dimmer switch signal/ON or OFF	ON: Dimmer switch is ON (High Beam) or High flasher switch is ON OFF: Dimmer switch is OFF (Low Beam) or High flasher switch is OFF	-
   Head Light SW	Headlight control switch signal / ON or OFF	ON: Light control switch is in HEAD position OFF: Light control switch is not in 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 in OFF position	-

   OK

   Condition information can be displayed.

NG → See step   2 

OK → See step   5 

1. Remove the headlight dimmer switch assembly.
   Fig 1: Identifying Headlight Dimmer Switch Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according value(s) in the table below.
   1. Light Control Switch:

      Standard resistance

      Tester Connection	Condition	Specified Condition
      14 (T) - 16 (EL)	OFF	10 kΩ or higher
      13 (H) - 16 (EL)
      14 (T) - 16 (EL)	TAIL	Below 1 Ω
      13 (H) - 16 (EL)		10 kΩ or higher
      14 (T) - 16 (EL)	HEAD	Below 1 Ω
      13 (H) - 16 (EL)		Below 1 Ω

   2. Headlight Dimmer Switch Switch:

      Standard resistance

      Tester Connection	Condition	Specified Condition
      7 (HU) - 16 (EL)	HIGH BEAM	Below 1 Ω
      17 (HL) - 16 (EL)	LOW BEAM	Below 1 Ω
      7 (HU) - 8 (HF) - 16 (EL)	FLASH	Below 1 Ω

3. Reinstall the headlight dimmer switch assembly.

NG → See step   6 

OK: Go to next step 

1. Disconnect the E8 main body ECU connector.
   Fig 2: Checking Harness And Connector (Headlight Dimmer Switch - Main Body ECU)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the E20 headlight dimmer switch assembly connector.
3. Measure the resistance according value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   E20-8 (HF) - E8-7 (HF)	Always	Below 1 Ω
   E20-8 (HF) or E8-7 (HF) - Body ground	Always	10 kΩ or higher
   E20-14 (T) - E8-8 (TAIL)	Always	Below 1 Ω
   E20-14 (T) or E8-8 (TAIL) - Body ground	Always	10 kΩ or higher
   E20-13 (H) - E8-1 (HEAD)	Always	Below 1 Ω
   E20-13 (H) or E8-1 (HEAD) - Body ground	Always	10 kΩ or higher
   E20-7 (HU) - E8-2 (HU)*	Always	Below 1 Ω
   E20-7 (HU) or E8-2 (HU)* - Body ground	Always	10 kΩ or higher
   E20-16 (EL) - Body ground	Always	Below 1 Ω

   HINT: 

   *: w/ Daytime running light system

4. Reconnect the main body ECU connector.
5. Reconnect the headlight dimmer switch assembly connector.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

HINT: 

*: w/o Daytime running light system

1. Disconnect the E20 headlight dimmer switch assembly connector.
   Fig 3: Checking Harness And Connector (Headlight Dimmer Switch -- Headlight*)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the A23 and A24 headlight connectors.
3. Measure the resistance according value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   E20-17 (HL) - A23-1	Always	Below 1 Ω
   E20-17 (HL) - A24-1	Always	Below 1 Ω
   E20-7 (HU) - A23-2	Always	Below 1 Ω
   E20-7 (HU) - A24-2	Always	Below 1 Ω

4. Reconnect the headlight dimmer switch assembly connector.
5. Reconnect the headlight connectors.

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   7