Headlight Relay Circuit

LIGHTING: LIGHTING SYSTEM: Headlight Relay Circuit

Headlight Relay Circuit

DESCRIPTION

The headlight relay is turned on by operating the headlight switch.
When the theft deterrent system is activated, it causes the ECU to turn the headlight relay on and off repeatedly at approximately 0.25 second intervals to flash the headlights.
In this condition, if any of the following operations is performed, the ECU turns the headlight relay off to stop the headlight from flashing:

- Unlock the driver door with a key.
- Turn the engine switch on (ACC or IG).
- Unlock the doors with the wireless door lock control system.

WIRING DIAGRAM









INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Body Electrical / Body / Active Test.
(e) Check the operation.

Body (Main Body ECU RH)





OK:
Headlight assembly (low) illuminates.
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG -- Continue to next step.
2. INSPECT FUSE (H-LP L LWR, H-LP R LWR)
(a) Remove the H-LP L LWR fuse from the engine room No. 2 relay block.
(b) Remove the H-LP R LWR fuse from the engine room No. 2 relay block.
(c) Measure the resistance of the fuses.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.
3. INSPECT HEAD LP RELAY




(a) Remove the HEAD LP relay from the engine room No. 1 relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:






NG -- REPLACE HEAD LP RELAY
OK -- Continue to next step.
4. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU RH - BATTERY)




(a) Disconnect the RL main body ECU RH connector.
(b) Measure the voltage according to the value(s) in the table below.
Standard voltage:






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - BATTERY AND BODY GROUND)




(a) Check the wire harness between the headlight (Low LH) and battery, and the headlight (Low LH) and body ground.
(1) Disconnect the B12 headlight connector.
(2) Measure the voltage and resistance according to the value(s) in the table below.
Standard voltage:






Standard resistance:









(b) Check the wire harness between the headlight (Low RH) and battery, and the headlight (Low RH) and body ground.
(1) Disconnect the B2 headlight connector.
(2) Measure the voltage and resistance according to the value(s) in the table below.
Standard voltage:






Standard resistance:






OK -- REPLACE HEADLIGHT ASSEMBLY (LOW LH OR LOW RH)
NG -- Continue to next step.
6. CHECK HARNESS AND CONNECTOR (HEADLIGHT (LOW LH OR LOW RH) - HEAD LP RELAY)




(a) Check the harness and the connectors between the headlight (Low LH or Low RH) and the HEAD LP relay.
(1) Disconnect the B12 headlight connector.
(2) Remove the HEAD LP relay from the engine room No. 1 relay block.
(3) Measure the resistance according to the value(s) in the table below.
Standard resistance (Check for open):






Standard resistance (Check for short):






NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- REPLACE MAIN BODY ECU RH (COWL SIDE J/B RH)