LIGHTING SYSTEM Light Control Switch Circuit

DESCRIPTION

• This circuit is only for vehicles with the daytime running light system or with automatic light control system.

  Tech Tips

  
  

  • For vehicles with the daytime running light system or with automatic light control system, the main body ECU receives switch signals to control the exterior lights (headlights, taillights, front fog light and rear fog light).

  • For vehicles without the daytime running light system and without automatic light control system, the exterior lights (headlights, taillights, front fog lights, and rear fog light) are not controlled by the main body ECU. Perform troubleshooting according to the Problem Symptoms Table Click here.

• The main body ECU receives the following signals:




• Light control switch TAIL, HEAD, or AUTO signal

• Dimmer switch HIGH or HIGH FLASH (PASS) signal

• Front fog light switch signal

• Rear fog light switch signal

  Tech Tips

  When performing troubleshooting, inspect the switch that is related to the malfunction. For example, if both right and left low beam headlights do not illuminate, read the light control switch HEAD signal value only in the data list. If the value is normal, perform the headlight relay active test.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. READ VALUE USING INTELLIGENT TESTER

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the tester on.

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

   5. According to the display on the tester, read the Data List.

      Main Body

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      Dimmer 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	-
      Rear Fog Light SW	Rear fog light switch signal ON or OFF	ON: Rear fog light switch ON OFF: Rear fog light switch OFF	-
      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 signal ON or OFF	ON: Light control switch in AUTO OFF: Light control switch not in AUTO	-
      Head Light SW (Head)	Light control switch HEAD signal ON or OFF	ON: Light control switch in HEAD OFF: Light control switch not in HEAD	-
      Head Light SW (Tail)	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

   INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY Click here

   OK

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

2. INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

   
   
   1. 

      Text in Illustration

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

      Remove the headlight dimmer switch assembly.

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

      Standard Resistance
      Light Control Switch Tester Connection Switch Condition Specified Condition 18 (T) - 12 (E) 18 (T) - 19 (A) 19 (A) - 20 (H) OFF 10 kΩ or higher 18 (T) - 12 (E) TAIL Below 1 Ω 18 (T) - 12 (E) HEAD Below 1 Ω 18 (T) - 20 (H) Below 1 Ω 19 (A) - 12 (E) AUTO Below 1 Ω
      Dimmer Switch Tester Connection Switch Condition Specified Condition 17 (HF) - 12 (E) HIGH FLASH Below 1 Ω 11 (HU) - 12 (E) Below 1 Ω 11 (HU) - 12 (E) HIGH Below 1 Ω
      Front 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
      Rear Fog Light Switch Tester Connection Switch Condition Specified Condition 2 (B) - 3 (LFG) OFF 10 kΩ or higher 2 (B) - 3 (LFG) ON Below 1 Ω

   3. Reinstall the headlight dimmer switch assembly.

   
   

   NG

   REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY Click here

   OK

3. CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH - MAIN BODY ECU AND BODY GROUND)

   
   
   1. 

      Text in Illustration

      *1	Front view of wire harness connector (to Headlight Dimmer Switch Assembly)
      *2	Front view of wire harness connector (to Main Body ECU)

      Disconnect the D24 headlight dimmer switch assembly connector.

   2. Disconnect the D42 main body ECU connectors.

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

      Standard Resistance

      Tester Connection Condition Specified Condition D24-2 (B) - D42-1 (RFOG) Always Below 1 Ω D24-2 (B) - Body ground Always 10 kΩ or higher D24-4 (BFG) - D42-27 (FFOG) Always Below 1 Ω D24-4 (BFG) - Body ground Always 10 kΩ or higher D24-11 (HU) - D42-5 (HU) Always Below 1 Ω D24-11 (HU) - Body ground Always 10 kΩ or higher D24-17 (HF) - D42-8 (HF) Always Below 1 Ω D24-17 (HF) - Body ground Always 10 kΩ or higher D24-18 (T) - D42-30 (TAIL) Always Below 1 Ω D24-18 (T) - Body ground Always 10 kΩ or higher D24-19 (A) - D42-28 (A) Always Below 1 Ω D24-19 (A) - Body ground Always 10 kΩ or higher D24-20 (H) - D42-29 (HEAD) Always Below 1 Ω D24-20 (H) - Body ground Always 10 kΩ or higher D24-3 (LFG) - Body ground Always Below 1 Ω D24-12 (E) - Body ground Always Below 1 Ω

   4. Reconnect the headlight dimmer switch assembly connector.

   5. Reconnect the main body ECU connectors.

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

   REPLACE MAIN BODY ECU Click here