Headlight Dimmer Switch Circuit [10/2014 - 10/2015]: 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 / 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 position OFF: Dimmer switch in low position	-
   Passing Light SW	Dimmer switch high flash position (pass) signal/ON or OFF	ON: Dimmer switch in high flash position OFF: Dimmer switch not in high flash position	-
   Front Fog Light SW*1	Fog light switch front position signal/ON or OFF	ON: Fog light switch in front position OFF: 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	-

   • *1: w/ Front Fog Light

   OK

   Normal conditions listed above are displayed.

Result: 

OK 

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE 

(Refer to PROBLEM SYMPTOMS TABLE [10/2014 - 10/2015] )

Result: 

NG 

See step  2

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 [10/2014 - ] ).
2. Measure the resistance according to the value(s) in the table below.

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   Standard Resistance

   LIGHT CONTROL SWITCH
   
   

   Tester Connection	Condition	Specified Condition
   18 (T) - 15 (EL)	Light control switch off*1 or DRL OFF*2	10 kΩ or higher
   19 (H) - 15 (EL)	Light control switch off*1 or DRL OFF*2	10 kΩ or higher
   20 (A) - 15 (EL)	Light control switch off*1 or DRL OFF*2	10 kΩ or higher
   18 (T) - 15 (EL)	Light control switch in tail position	Below 1 Ω
   18 (T) - 15 (EL)	Light control switch in head position	Below 1 Ω
   19 (H) - 15 (EL)	Light control switch in head position	Below 1 Ω
   20 (A) - 15 (EL)	Light control switch in AUTO position	Below 1 Ω

   DIMMER SWITCH
   
   

   Tester Connection	Condition	Specified Condition
   14 (HU) - 15 (EL)	Dimmer switch in low position	10 kΩ or higher
   14 (HU) - 15 (EL)	Dimmer switch in high position	Below 1 Ω
   14 (HU) - 15 (EL)	Dimmer switch in high flash position	Below 1 Ω
   17 (HF) - 15 (EL)	Dimmer switch in high flash position	Below 1 Ω

   FOG LIGHT SWITCH*3
   
   

   Tester Connection	Condition	Specified Condition
   9 (BFG) - 8 (LFG)	Front fog light switch off	10 kΩ or higher
   9 (BFG) - 8 (LFG)	Front fog light switch in front position	Below 1 Ω

   • *1: w/o DRL OFF Switch
   • *2: w/ DRL OFF Switch
   • *3: w/ Front Fog Light
   TEXT IN ILLUSTRATION
   
   

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

Result: 

NG 

REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY 

(Refer to REMOVAL [10/2014 - ] )

Result: 

OK 

See step  3

1. Disconnect the D6 main body ECU (multiplex network body ECU) connector.
2. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   D18-9 (BFG)*1 - D6-27 (FFOG)*1	Always	Below 1 Ω
   D18-14 (HU) - D6-5 (HU)	Always	Below 1 Ω
   D18-17 (HF) - D6-8 (HF)	Always	Below 1 Ω
   D18-18 (T) - D6-30 (TAIL)	Always	Below 1 Ω
   D18-19 (H) - D6-29 (HEAD)	Always	Below 1 Ω
   D18-20 (A) - D6-28 (A)	Always	Below 1 Ω
   D18-9 (BFG)*1 - Body ground	Always	10 kΩ or higher
   D18-14 (HU) - Body ground	Always	10 kΩ or higher
   D18-17 (HF) - Body ground	Always	10 kΩ or higher
   D18-18 (T) - Body ground	Always	10 kΩ or higher
   D18-19 (H) - Body ground	Always	10 kΩ or higher
   D18-20 (A) - Body ground	Always	10 kΩ or higher
   D18-15 (EL) - Body ground	Always	Below 1 Ω
   D18-8 (LFG)*1 - Body ground	Always	Below 1 Ω

   • *1: w/ Front Fog Light

Result: 

OK 

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) 

(Refer to REMOVAL [10/2014 - ] )

Result: 

NG 

REPAIR OR REPLACE HARNESS OR CONNECTOR