Toyota 4Runner: Problem Symptoms Table

Toyota 4Runner Service Manual / Vehicle Exterior / Lighting (ext) / Lighting System / Problem Symptoms Table

PROBLEM SYMPTOMS TABLE

HINT:

Use the table below to help determine the cause of problem symptoms. If multiple suspected areas are listed, the potential causes of the symptoms are listed in order of probability in the "Suspected Area" column of the table. Check each symptom by checking the suspected areas in the order they are listed. Replace parts as necessary.

Headlight System

Symptom	Suspected Area	See page
Low beam headlight on one side does not illuminate.	H-LP LH-LO fuse or H-LP RH-LO fuse	-
	Headlight bulb (Low)	-
	Harness or connector	-
Both left and right low beam headlights do not illuminate.	Headlight relay circuit
	Headlight dimmer switch circuit
	Harness or connector	-
	Main body ECU (Multiplex network body ECU)	-
High beam headlight on one side does not illuminate.	H-LP LH-HI fuse or H-LP RH-HI fuse	-
	Headlight bulb (High)	-
	Harness or connector	-
Both left and right high beam headlights do not illuminate (low beam headlights are normal).	H-LP HI fuse	-
	Headlight (HI-BEAM) circuit
	Headlight dimmer switch circuit
	Harness or connector	-
	Main body ECU (Multiplex network body ECU)	-
High beam headlights do not illuminate with "High Flash" function (passing function).	Headlight dimmer switch circuit
	Main body ECU (Multiplex network body ECU)	-
Low beam headlights or high beam headlights do not turn off.	Headlight dimmer switch assembly
	Harness or connector	-
	Main body ECU (Multiplex network body ECU)	-

Taillight System

Symptom	Suspected Area	See page
Clearance light does not illuminate.	Clearance light bulb	-
	Clearance light socket	-
	Harness or connector	-
Front side marker light does not illuminate.	Front side marker light bulb	-
	Front side marker light socket	-
	Harness or connector	-
Taillight does not illuminate.	Rear combination light assembly	-
Taillight does not illuminate.	Harness or connector	-
License plate light does not illuminate.	License plate light bulb	-
License plate light does not illuminate.	Harness or connector	-
All lights do not illuminate.	TAIL fuse	-
	Taillight relay circuit
	Headlight dimmer switch circuit
	Harness or connector	-
	Main body ECU (Multiplex network body ECU)	-

Stop Light System

Symptom	Suspected Area	See page
Stop light on one side does not illuminate.	Rear combination light assembly	-
Stop light on one side does not illuminate.	Harness or connector	-
Center stop light does not illuminate.	Center stop light assembly
Center stop light does not illuminate.	Harness or connector	-
All lights do not operate.	STOP fuse	-
	Stop light switch assembly
	Harness or connector	-

Front Fog Light System

Symptom	Suspected Area	See page
Front fog light on one side does not illuminate.	Front fog light bulb	-
Front fog light on one side does not illuminate.	Harness or connector	-
Both left and right front fog lights do not illuminate (taillight is normal).	FOG FR fuse	-
	Front fog light circuit
	Headlight dimmer switch circuit
	Harness or connector	-
	Main body ECU (Multiplex network body ECU)	-

Turn Signal and Hazard Warning Light System

Symptom	Suspected Area	See page
Hazard warning lights do not operate (turn signal lights are normal).	TRN&HAZ fuse	-
	Hazard warning signal switch assembly
	Turn signal flasher assembly
	Harness or connector	-
Turn signal lights do not operate (hazard warning lights are normal).	IG1 fuse	-
	Headlight dimmer switch assembly (Turn signal switch)
	Turn signal flasher assembly
	Harness or connector	-
Hazard warning lights and turn signal lights do not operate.	TRN&HAZ fuse and IG1 fuse	-
	Turn signal flasher assembly
	Harness or connector	-
Turn signal lights do not operate in one direction.	Headlight dimmer switch assembly (Turn signal switch)
	Turn signal flasher assembly
	Harness or connector	-
Front turn signal light does not illuminate.	Front turn signal light bulb	-
Front turn signal light does not illuminate.	Harness or connector	-
Side turn signal light does not illuminate.	Side turn signal light assembly
Side turn signal light does not illuminate.	Harness or connector	-
Rear turn signal light does not illuminate.	Rear turn signal light bulb	-
Rear turn signal light does not illuminate.	Harness or connector	-

Back-up Light System

Symptom	Suspected Area	See page
Back-up light on one side does not illuminate.	Back-up light bulb	-
Back-up light on one side does not illuminate.	Harness or connector	-
Both left and right back-up lights do not illuminate.	BKUP LP fuse and ECU-IG NO. 1 fuse	-
	BK/LP relay	-
	Park/neutral position switch assembly (for A750E Automatic Transmission)
	Park/neutral position switch assembly (for A750F Automatic Transmission)
	Harness or connector	-

Automatic Light Control System (w/ Automatic Light Control System)

Symptom	Suspected Area	See page
Automatic light control system does not operate.	Check for DTCs
	Headlight dimmer switch circuit
	IG signal circuit
	Main body ECU (Multiplex network body ECU)	-

Light Auto Turn Off System

Symptom	Suspected Area	See page
Light auto turn off system does not operate.	Headlight dimmer switch circuit
	Door courtesy switch circuit (Driver side)
	IG signal circuit
	Main body ECU (Multiplex network body ECU)	-

Daytime Running Light System

Symptom	Suspected Area	See page
Daytime running light system does not operate (high beam headlights are normal).	Headlight (High beam) circuit
	Headlight dimmer switch circuit
	IG signal circuit
	Main body ECU (Multiplex network body ECU)	-

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