Headlight Signal Circuit
LIGHTING: LIGHTING SYSTEM: Headlight Signal Circuit
- Headlight Signal Circuit
DESCRIPTION
The main body ECU receives a headlight Lo switch information signal from the light control switch, and illuminates the headlight low beam.
WIRING DIAGRAM
INSPECTION PROCEDURE
PROCEDURE
1. PERFORM ACTIVE TEST USING TECHSTREAM (HEADLIGHT)
(a) Operate the Techstream according to the steps on the display and select "Active Test".
Main Body ECU
OK:
Headlight low beam turns on / turns off.
NG -- INSPECT FUSE (HEAD LL, HEAD RL)
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE Symptom Related Diagnostic Procedures
2. INSPECT FUSE (HEAD LL, HEAD RL)
(a) Remove the HEAD LL and HEAD RL fuses from the engine room junction block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE FUSE
OK -- Continue to next step.
3. CHECK HARNESS AND CONNECTOR (HEADLIGHT LOW BULB - BATTERY)
(a) for LH:
(1) Disconnect the A10 headlight connector.
(2) Measure the voltage according to the value(s) in the table below.
Standard voltage:
(b) for RH:
(1) Disconnect the A11 headlight connector.
(2) Measure the voltage according to the value(s) in the table below.
Standard voltage:
NG -- INSPECT HEADLIGHT RELAY (HEAD)
OK -- REPAIR OR REPLACE HARNESS OR CONNECTOR (HEADLIGHT LOW BULB - BODY GROUND)
4. INSPECT HEADLIGHT RELAY (HEAD)
(a) Remove the headlight relay from the engine room relay block.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
NG -- REPLACE HEADLIGHT RELAY
OK -- Continue to next step.
5. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - BATTERY)
(a) Remove the headlight relay from the engine room relay block.
(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.
6. CHECK HARNESS AND CONNECTOR (HEADLIGHT RELAY - HEADLIGHT LOW BULB)
(a) Remove the headlight relay from the engine room relay block.
(b) for LH:
(1) Disconnect the A10 headlight connector.
(2) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(c) for RH:
(1) Disconnect the A11 headlight connector.
(2) 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.
7. CHECK HEADLIGHT (LOW BEAM)
(a) Disconnect the DB ECU connector.
(b) Using a service wire, connect DB-18 (HRLY) on the wire harness side and body ground.
(c) Check that the headlight low beam illuminates.
OK:
Headlight low beam illuminates.
NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR (HEADLIGHT RELAY - MAIN BODY ECU)
OK -- REPLACE MAIN BODY ECU