Headlight Relay Circuit

LIGHTING: LIGHTING SYSTEM: Headlight Relay Circuit
- Headlight Relay Circuit

DESCRIPTION

* The main body receives the light control switch HEAD signal to control the headlight relays. The headlight relays are installed in the power distributor (engine room junction block assembly).

* When the light control switch is in AUTO position, the main body ECU receives the ambient light level signal from the automatic light control sensor to control the headlight relays.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect Techstream to the DLC3.

(b) Turn the ignition switch on (IG).

(c) Turn Techstream on.

(d) Select the following menu items: Body Electrical / Main Body / Active Test.

(e) Check that the relays operate.

Main Body:





OK:

Headlight relays operate. (Low beam headlights illuminate.)

NG -- INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY

OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures

2. INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY

(a) Remove the H-LP LH LO fuse and H-LP RH LO fuse from the engine room junction block assembly.





(b) Measure the voltage between the loading slot of each fuse and body ground.

Standard voltage:





NG -- INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY

OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (FUSE - BODY GROUND)

3. INSPECT ENGINE ROOM JUNCTION BLOCK ASSEMBLY

(a) Remove the engine room junction block assembly from the engine room relay block.





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

Standard voltage:





NG -- REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY
OK -- Continue to next step.

4. CHECK HARNESS AND CONNECTOR (BATTERY - ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 2G engine room junction block assembly 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 (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - MAIN BODY ECU)

(a) Disconnect the 2D engine room junction block assembly connector.





(b) Disconnect the 1D instrument panel junction block connector.

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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

6. CHECK HARNESS AND CONNECTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY - BODY GROUND)

(a) Disconnect the 2E engine room junction block assembly connector.





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

Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE MAIN BODY ECU (INSTRUMENT PANEL JUNCTION BLOCK)