Toyota 4Runner: Headlight Dimmer Switch Circuit

Toyota 4Runner Service Manual / Vehicle Exterior / Lighting (ext) / Lighting System / Headlight Dimmer Switch Circuit

DESCRIPTION

The main body ECU receives the following signals:

Headlight dimmer switch tail, head, AUTO*, high or high flash signal
Front fog light switch signal

*: w/ Automatic Light Control System

WIRING DIAGRAM

PROCEDURE

1.	READ VALUE USING TECHSTREAM (HEADLIGHT DIMMER SWITCH)

(a) Using the Techstream, read the Data List (See page ).

Main Body

Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
Dimmer SW	Headlight dimmer switch high signal / ON or OFF	ON: Headlight dimmer switch in high or high flash OFF: Headlight dimmer switch in low	-
Passing Light SW	Headlight dimmer switch high flash signal / ON or OFF	ON: Headlight dimmer switch in high flash OFF: Headlight dimmer switch not in high flash	-
Front Fog Light SW	Front fog light switch signal / ON or OFF	ON: Front fog light switch on OFF: Front fog light switch off	-
Auto Light SW*	Headlight dimmer switch AUTO signal / ON or OFF	ON: Headlight dimmer switch in AUTO OFF: Headlight dimmer switch not in AUTO	-
Head Light SW (Head)	Headlight dimmer switch head signal / ON or OFF	ON: Headlight dimmer switch in head OFF: Headlight dimmer switch not in head	-
Head Light SW (Tail)	Headlight dimmer switch tail signal / ON or OFF	ON: Headlight dimmer switch in tail or head OFF: Headlight dimmer switch not in tail or head	-

*: w/ Automatic Light Control System

OK:

The display is as specified in the normal condition column.

PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE

2.	INSPECT HEADLIGHT DIMMER SWITCH ASSEMBLY

(a) Remove the headlight dimmer switch (See page ).

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

Standard Resistance:

Tester Connection	Switch Condition	Specified Condition
4 (BFG) - 3 (LFG)	Fog light switch on	Below 1 Ω
11 (HU) - 12 (EL)	Headlight dimmer switch high	Below 1 Ω
11 (HU) - 12 (EL)	Headlight dimmer switch high flash	Below 1 Ω
17 (HF) - 12 (EL)	Headlight dimmer switch high flash	Below 1 Ω
18 (T) - 12 (EL)	Headlight dimmer switch tail	Below 1 Ω
18 (T) - 12 (EL)	Headlight dimmer switch head	Below 1 Ω
19 (A) - 12 (EL)*	Headlight dimmer switch AUTO	Below 1 Ω
20 (H) - 12 (EL)	Headlight dimmer switch head	Below 1 Ω
4 (BFG) - 3 (LFG)	Fog light switch off	10 kΩ or higher
18 (T) - 12 (EL)	Headlight dimmer switch off	10 kΩ or higher
19 (A) - 12 (EL)*
20 (H) - 12 (EL)

*: w/ Automatic Light Control System

Text in Illustration

*A	w/ Automatic Light Control System

REPLACE HEADLIGHT DIMMER SWITCH ASSEMBLY

3.	CHECK HARNESS AND CONNECTOR (HEADLIGHT DIMMER SWITCH ASSEMBLY - MAIN BODY ECU AND BODY GROUND)

(a) Disconnect the F22 headlight dimmer switch connector.

(b) Disconnect the F9 main body ECU connector.

Standard Resistance:

Tester Connection	Condition	Specified Condition
F22-4 (BFG) - F9-27 (FFOG)	Always	Below 1 Ω
F22-11 (HU) - F9-5 (HU)	Always	Below 1 Ω
F22-17 (HF) - F9-8 (HF)	Always	Below 1 Ω
F22-18 (T) - F9-30 (TAIL)	Always	Below 1 Ω
F22-19 (A) - F9-28 (A)*	Always	Below 1 Ω
F22-20 (H) - F9-29 (HEAD)	Always	Below 1 Ω
F22-4 (BFG) - Body ground	Always	10 kΩ or higher
F22-11 (HU) - Body ground	Always	10 kΩ or higher
F22-17 (HF) - Body ground	Always	10 kΩ or higher
F22-18 (T) - Body ground	Always	10 kΩ or higher
F22-19 (A) - Body ground*	Always	10 kΩ or higher
F22-20 (H) - Body ground	Always	10 kΩ or higher
F22-12 (EL) - Body ground	Always	Below 1 Ω
F22-3 (LFG) - Body ground	Always	Below 1 Ω

*: w/ Automatic Light Control System

REPLACE MAIN BODY ECU (MULTIPLEX NETWORK BODY ECU)

REPAIR OR REPLACE HARNESS OR CONNECTOR

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