High Beam Headlight Circuit

LIGHTING (EXT): LIGHTING SYSTEM: High Beam Headlight Circuit
- High Beam Headlight Circuit

DESCRIPTION

The main body ECU (multiplex network body ECU) controls the high beam headlights.

WIRING DIAGRAM





INSPECTION PROCEDURE

NOTICE:
Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE

1. CHECK OPERATION (LOW BEAM HEADLIGHTS)

(a) Check the operation of the low beam headlights.

OK:

Low beam headlights operate normally.

NG -- GO TO PROBLEM SYMPTOMS TABLE Exterior Lighting System
OK -- Continue to next step.

2. PERFORM ACTIVE TEST USING TECHSTREAM

(a) Connect the Techstream to the DLC3.

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

(c) Turn the Techstream on.

(d) Enter the following menus: Body Electrical / Main Body / Active Test.

(e) Check that the high beam headlights illuminate.

Main Body





OK:

High beam headlights illuminate.

NG -- CHECK HARNESS AND CONNECTOR (SHORT IN RELAY-DRIVEN CIRCUIT)

OK -- PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Exterior Lighting System

3. CHECK HARNESS AND CONNECTOR (SHORT IN RELAY-DRIVEN CIRCUIT)

HINT
When a short circuit occurs between the power distributor (engine room junction block assembly) and high beam headlight bulb, a fail-safe function operates to stop high beam headlight operation.

(a) Remove the H-LP RH HI fuse from the power distributor (engine room junction block assembly).

(b) Turn the light control switch to the head position and turn the dimmer switch to the high position.

(c) Check if the high beam headlight LH illuminates.

(d) Turn the dimmer switch to the low position.

(e) Install the H-LP RH HI fuse and remove the H-LP LH HI fuse.

(f) Turn the dimmer switch to the high position.

(g) Check if the high beam headlight RH illuminates.

OK:

Either high beam headlight LH or RH illuminates.

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

4. INSPECT POWER DISTRIBUTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY)

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





(b) Connect a positive (+) lead from the battery to terminal 3A-1.

(c) Connect a negative (-) lead from the battery to terminals 3C-5 and 3C-17.

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

Standard Voltage:





Text in Illustration





NG -- REPLACE POWER DISTRIBUTOR (ENGINE ROOM JUNCTION BLOCK ASSEMBLY) Components
OK -- Continue to next step.

5. CHECK HARNESS AND CONNECTOR (POWER DISTRIBUTOR - INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)

(a) Disconnect the 3C power distributor (engine room junction block assembly) connector.





(b) Disconnect the F12 main body ECU (multiplex network body ECU).

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

Standard Resistance:





Text in Illustration





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU) Components