LIGHTING SYSTEM Headlight Dimmer Switch Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) receives the following switch information:

• Light control switch in off, tail, head or AUTO position

• Dimmer switch in high, low or high flash (pass) position

• Fog light switch in front, rear or off position

WIRING DIAGRAM

1. 

PROCEDURE

1. READ VALUE USING GTS

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the power switch on (IG).

   3. Turn the GTS on.

   4. Enter the following menus: Body Electrical / Main Body / Data List.

   5. Read the display on the GTS.

      
      Body Electrical > Main Body > Data List

      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	-
      Rear Fog Light SW	Fog light switch rear position signal	ON or OFF	ON: Fog light switch in rear position OFF: Fog light switch off	-
      Front Fog Light SW	Fog light switch front position signal	ON or OFF	ON: Fog light switch in front position OFF: Fog light switch off	w/ Front Fog Light
      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	w/ Automatic Light Control
      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	-

      
      Body Electrical > Main Body > Data List

      Tester Display
      Dimmer SW
      Passing Light SW
      Rear Fog Light SW
      Front Fog Light SW
      Auto Light SW
      Head Light SW (Head)
      Head Light SW (Tail)

      OK
      Normal conditions listed above are displayed.

      Result
      Proceed to OK NG

   
   

   OK

   PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

   NG

2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

   Tech Tips

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

   
   

   1. Remove the headlight dimmer switch assembly.

      Click here

   2. 

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

      Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Light Control Switch Tester Connection Condition Specified Condition 18 (T) - 15 (EL) Light control switch off 10 kΩ or higher 19 (H) - 15 (EL) Light control switch off 10 kΩ or higher 20 (A)*1 - 15 (EL) Light control switch off 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)*1 - 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 Tester Connection Condition Specified Condition 9 (BFG)*2 - 8 (LFG) Fog light switch off 10 kΩ or higher 9 (BFG)*2 - 8 (LFG) Fog light switch in front position Below 1 Ω 7 (B) - 8 (LFG) Fog light switch off 10 kΩ or higher 7 (B) - 8 (LFG) Fog light switch in rear position Below 1 Ω

      
      

      • *1: w/ Automatic Light Control

      • *2: w/ Front Fog Light

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY Click here

   OK

3. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU))

   
   

   1. Disconnect the E22 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 E8-9 (BFG)*2 - E22-27 (FFOG)*2 Always Below 1 Ω E8-7 (B) - E22-1 (RFOG) Always Below 1 Ω E8-14 (HU) - E22-5 (HU) Always Below 1 Ω E8-17 (HF) - E22-8 (HF) Always Below 1 Ω E8-18 (T) - E22-30 (TAIL) Always Below 1 Ω E8-19 (H) - E22-29 (HEAD) Always Below 1 Ω E8-20 (A)*1 - E22-28 (A)*1 Always Below 1 Ω E8-9 (BFG)*2 - Body ground Always 10 kΩ or higher E8-7 (B) - Body ground Always 10 kΩ or higher E8-14 (HU) - Body ground Always 10 kΩ or higher E8-17 (HF) - Body ground Always 10 kΩ or higher E8-18 (T) - Body ground Always 10 kΩ or higher E8-19 (H) - Body ground Always 10 kΩ or higher E8-20 (A)*1 - Body ground Always 10 kΩ or higher E8-15 (EL) - Body ground Always Below 1 Ω E8-8 (LFG) - Body ground Always Below 1 Ω

      
      

      • *1: w/ Automatic Light Control

      • *2: w/ Front Fog Light

      Result
      Proceed to OK NG

   
   

   OK

   REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for LHD: Click here REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) for RHD: Click here

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR