Light Control Switch Circuit: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to ON.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Main Body / Data List.
5. Read the display on the Techstream.
   MAIN BODY
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Dimmer SW	Dimmer switch high position signal/ON or OFF	ON: Dimmer switch in high or high flash (pass) position OFF: Dimmer switch in low position	-
   Passing Light SW	Dimmer switch high flash (pass) position signal/ON or OFF	ON: Dimmer switch in high flash (pass) position OFF: Dimmer switch not in high flash (pass) position	-
   Front Fog Light SW	Front fog light switch signal/ON or OFF	ON: Front fog light switch on OFF: Front fog light switch off	-
   Auto Light SW	Light control switch AUTO position signal/ON or OFF	ON: Light control switch in AUTO position OFF: Light control switch not in AUTO position	-
   Head Light SW (Head)	Light control switch head position signal/ON or OFF	ON: Light control switch in head position OFF: Light control switch not in head position	-
   Head Light SW (Tail)	Light control switch tail position signal/ON or OFF	ON: Light control switch in tail or head position OFF: Light control switch in neither tail nor head position	-

   OK

   Normal conditions listed above are displayed.

NG → See step   2 

OK → See step   4 

HINT: 

Inspect the items that did not change as a result of monitoring the Data List.

1. Remove the headlight dimmer switch assembly. Refer to REMOVAL .
   Fig 1: Inspecting Headlight Dimmer Switch Assembly

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   LIGHT CONTROL SWITCH
   
   

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

   DIMMER SWITCH
   
   

   Tester Connection	Switch Condition	Specified Condition
   11 (HU) - 12 (EL)	LOW	10 kΩ or higher
   11 (HU) - 12 (EL)	HIGH	Below 1 Ω
   12 (EL) - 17 (HF)	HIGH FLASH	Below 1 Ω

   FOG LIGHT SWITCH
   
   

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

   TEXT IN ILLUSTRATION
   
   

   *a	Component without harness connected: (Headlight Dimmer Switch Assembly)

NG → See step   5 

OK: Go to next step 

1. Disconnect the D19 headlight dimmer switch assembly connector.
2. Disconnect the D13 main body ECU connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   D19-4 (BFG) - D13-27 (FFOG)	Always	Below 1 Ω
   D19-11 (HU) - D13-5 (HU)	Always	Below 1 Ω
   D19-17 (HF) - D13-8 (HF)	Always	Below 1 Ω
   D19-18 (T) - D13-30 (TAIL)	Always	Below 1 Ω
   D19-19 (A) - D13-28 (A)	Always	Below 1 Ω
   D19-20 (H) - D13-29 (HEAD)	Always	Below 1 Ω
   D19-3 (LFG) - Body ground	Always	Below 1 Ω
   D19-4 (BFG) - Body ground	Always	10 kΩ or higher
   D19-11 (HU) - Body ground	Always	10 kΩ or higher
   D19-17 (HF) - Body ground	Always	10 kΩ or higher
   D19-18 (T) - Body ground	Always	10 kΩ or higher
   D19-19 (A) - Body ground	Always	10 kΩ or higher
   D19-20 (H) - Body ground	Always	10 kΩ or higher
   D19-12 (EL) - Body ground	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → See step   6