Lighting System Headlight Relay Circuit

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (MAIN BODY ECU)

CHECK WIRE HARNESS (DIMMER SWITCH - MAIN BODY ECU AND BODY GROUND)

INSPECT HEADLIGHT DIMMER SWITCH

INSPECT FUSE (HEAD LL, HEAD RL)

INSPECT HEADLIGHT RELAY

INSPECT BULB (HEADLIGHT BULB)

CHECK VEHICLE CONDITION

CHECK HEADLIGHT UNIT

CHECK WIRE HARNESS (MAIN BODY ECU - BATTERY)

CHECK INSTRUMENT PANEL JUNCTION BLOCK (MAIN BODY ECU)

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

1. Connect the intelligent tester to the DLC3.
   

2. Turn the ignition switch on (IG) and press the intelligent tester main switch ON.
   

3. Select the item below in the ACTIVE TEST and then check that the relay operates.
   
   

   Main body ECU:

   
   

   Item	Test Details: Display (Range)	Diagnostic Note
   Head Light	Headlight Relay ON/OFF	-

   OK:

   Headlights (Low) come on
   

1. Disconnect the E20 main body ECU connector.
   

2. Disconnect the E15 headlight dimmer switch connector.
   

3. Measure the resistance of the wire harness side connectors.
   
   

   Standard resistance:

   for LH side

   Tester Connection	Specified Condition
   E20-12 (HEAD) - E15-20 (H)	Below 1 Ω
   E15-12 (EL) - Body ground	Below 1 Ω
   E20-12 (HEAD) - Body ground	10 kΩ or higher

   for RH side

   Tester Connection	Specified Condition
   E20-12 (HEAD) - E15-11 (H)	Below 1 Ω
   E15-19 (EL) - Body ground	Below 1 Ω
   E20-12 (HEAD) - Body ground	10 kΩ or higher

1. Remove the headlight dimmer switch.
   

2. Measure the resistance of the switch.
   
   

   Standard resistance:

   for LH side

   Tester Connection	Switch Condition	Specified Condition
   18 (T) - 12 (EL)	Light control switch TAIL	Below 1 Ω
   18 (T) - 12 (EL)	Light control switch OFF	10 kΩ or higher
   20 (H) - 12 (EL)	Light control switch HEAD	Below 1 Ω
   20 (H) - 12 (EL)	Light control switch OFF	10 kΩ or higher
   16 (HL) - 12 (EL)	Dimmer switch LOW	Below 1 Ω
   16 (HL) - 12 (EL)	Dimmer switch HIGH	10 kΩ or higher

   for RH side

   Tester Connection	Switch Condition	Specified Condition
   13 (T) - 19 (EL)	Light control switch TAIL	Below 1 Ω
   13 (T) - 19 (EL)	Light control switch OFF	10 kΩ or higher
   11 (H) - 19 (EL)	Light control switch HEAD	Below 1 Ω
   11 (H) - 19 (EL)	Light control switch OFF	10 kΩ or higher
   15 (HL) - 19 (EL)	Dimmer switch LOW	Below 1 Ω
   15 (HL) - 19 (EL)	Dimmer switch HIGH	10 kΩ or higher

1. Remove the HEAD LL fuse and HEAD RL fuse from the engine room No. 2 relay block.
   

2. Measure the resistance of the fuses.
   

   Standard resistance:

   Below 1 Ω
   

1. Remove the headlight relay from the engine room No. 2 relay block.
   

2. Measure the resistance of the relay.
   

   Standard resistance:

   Tester Connection	Specified Condition
   3 - 5	10 kΩ or higher
   3 - 5	Below 1 Ω (Battery voltage applied to terminals 1 and 2)

1. Remove the headlight bulbs.
   

2. Connect the positive (+) lead from the battery to terminal 2 and the negative (-) lead to terminal 1, then check that the bulb illuminates.
   

   OK:

   Bulb illuminates.
   

1. Check the vehicle condition.
   

   Result

   Result	Proceed to
   w/ Hood Moulding	A
   w/o Hood Moulding	B

1. Disconnect the A73 (for LH) and A78 (for RH) headlight (Low) connectors.
   

2. Connect the positive (+) lead from the battery to terminal 2 and the negative (-) lead to terminal 1, then check that the headlights (Low) come on.
   

   OK:

   Headlights (Low) come on.
   

1. Disconnect the E18 main body ECU connector.
   

2. Measure the voltage of the wire harness side connector.
   

   Standard voltage:

   Tester Connection	Specified Condition
   E18-20 (HRLY) - Body ground	11 to 14 V

1. Measure the voltage of the ECU.
   

   Standard voltage:

   Tester Connection	Condition	Specified Condition
   E18-20 (HRLY) - Body ground	Light control switch OFF	11 to 14 V
   E18-20 (HRLY) - Body ground	Light control switch HEAD	Below 1 V