Light Control Switch Circuit: Procedure

1. Connect Techstream to the DLC3.
2. Turn the ignition switch on (IG).
3. Turn Techstream on.
4. Select the following menu items: Body Electrical / Main Body / Data List.
5. Read the display on Techstream.
   MAIN BODY:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Dimmer Hi SW	Dimmer switch HIGH signal / ON or OFF	ON: Dimmer switch in HIGH or HIGH FLASH OFF: Dimmer switch in LOW	-
   Passing Light SW	Dimmer switch HIGH FLASH signal / ON or OFF	ON: Dimmer switch in HIGH FLASH OFF: Dimmer switch not in HIGH FLASH	-
   Front Fog Light SW	Front fog light switch signal / ON or OFF	ON: Fog light switch ON OFF: Fog light switch OFF	-
   Light Auto SW	Light control switch AUTO signal / ON or OFF	ON: Light control switch in AUTO OFF: Light control switch not in AUTO	-
   Headlight SW	Light control switch HEAD signal / ON or OFF	ON: Light control switch in HEAD OFF: Light control switch not in HEAD	-
   Taillight SW	Light control switch TAIL signal / ON or OFF	ON: Light control switch in TAIL or HEAD OFF: Light control switch in neither TAIL nor HEAD	-

   OK

   Normal conditions listed above are displayed.

NG → See step   2 

OK → See step   4 

1. Inspect the headlight dimmer switch assembly. Refer to INSPECTION .

   OK

   Headlight dimmer switch assembly is normal.

NG → REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY 

OK: Go to next step 

1. Disconnect the D13 headlight dimmer switch assembly connector.
   Fig 1: Checking Harness And Connector (Instrument Panel Junction Block - Switch Assembly)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Disconnect the D7 and D8 main body ECU connectors.
3. Disconnect the 1N instrument panel junction block connector.
4. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   D13-4 (BFG) - D7-28 (FFOG)	Always	Below 1 Ω
   D13-11 (HU) - 1N-2 (HU)	Always	Below 1 Ω
   D13-17 (HF) - D8-13 (HF)	Always	Below 1 Ω
   D13-18 (T) - D8-23 (TAIL)	Always	Below 1 Ω
   D13-19 (A) - D8-21 (A)	Always	Below 1 Ω
   D13-20 (H) - D7-17 (HEAD)	Always	Below 1 Ω
   D13-3 (LFG) - Body ground	Always	10 kΩ or higher
   D13-4 (BFG) - Body ground	Always	10 kΩ or higher
   D13-11 (HU) - Body ground	Always	10 kΩ or higher
   D13-17 (HF) - Body ground	Always	10 kΩ or higher
   D13-18 (T) - Body ground	Always	10 kΩ or higher
   D13-19 (A) - Body ground	Always	10 kΩ or higher
   D13-20 (H) - Body ground	Always	10 kΩ or higher
   D13-12 (EL) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)