Lighting System Symptom Diagnosis

Precautions: Precautions for Headlight Auto Leveling System Service · Precautions for Body, Cab and Accessories · General safety (00)

Condition	Possible Cause	Action
Only one low-beam headlight lights up	Blown bulb (halogen headlight model)	Replace bulb.
Only one low-beam headlight lights up	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
Both low-beam headlights do not light up	Faulty lighting and turn signal switch	Refer to Lighting and Turn Signal Switch Inspection.
	Blown bulbs (halogen headlight model)	Replace bulbs.
	Faulty system circuit (including relay and fuses)	Repair circuit and replace relay and/or fuse.
Only one high-beam headlight lights up	Blown bulb	Replace bulb.
Only one high-beam headlight lights up	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
Both high-beam headlights do not light up	Blown bulbs	Replace bulbs.
	Faulty lighting and turn signal switch	Refer to Lighting and Turn Signal Switch Inspection.
	Faulty system circuit (including relay and fuses)	Repair circuit and replace relay and/or fuse.
Auto-on headlight system malfunctions (if equipped)	Wrong initialization of rain / light sensor	Refer to Rain / Light Sensor Initialization (If Equipped).
	Faulty BCM	Refer to Inspection of BCM and Its Circuits.
	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
	Faulty lighting and turn signal switch	Refer to Lighting and Turn Signal Switch Inspection.
	Faulty rain / light sensor	Refer to Scan Tool Data.
Headlight manual leveling system does not operate (if equipped)	Faulty system circuit (including relay and fuse)	Repair circuit and replace relay and/or fuse.
	Faulty headlight units (including headlight leveling actuators)	Refer to Headlight Leveling Actuator Inspection (If Equipped).
	Faulty headlight leveling switch	Refer to Headlight Leveling Switch Inspection (If Equipped).
Headlight auto leveling system does not operate (LED headlight model)	Faulty headlight auto leveling control module	Refer to Inspection of Headlight Auto Leveling Control Module and Its Circuit (LED Headlight Model).
	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
	Faulty rear vehicle height sensor	Refer to Vehicle Height Sensor Inspection (LED Headlight Model).
	Faulty headlight units (including headlight leveling actuators)	Refer to Headlight Leveling Actuator Inspection (If Equipped).
Fog lights do not light up (if equipped)	Faulty system circuit (including relays and fuses)	Repair circuit and replace relay and/or fuse.
	Blown bulbs	Replace bulbs.
	Faulty fog light switch	•Front fog light switch: refer to Front Fog Light Switch Inspection (If Equipped). •Rear fog light switch: refer to Lighting and Turn Signal Switch Inspection.
Dome light, spot light, luggage compartment light (if equipped) or foot light (if equipped) does not light up	Faulty BCM	Refer to Inspection of BCM and Its Circuits.
	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
	Blown bulbs	Replace bulbs.
	Faulty door switch	•Front and rear door switch: Refer to Front and Rear Door Switch Inspection. •Rear end door switch: Refer to “Rear End Door Switch” in Rear End Door Latch On-Vehicle Inspection.
Clearance lights, tail lights, license plate lights, DRL (if equipped) or LED DRL (if equipped) do not light up	Faulty system circuit (including relays and fuses)	Repair circuit and replace relay and/or fuse.
	Blown bulbs	Replace bulbs.
	Faulty lighting and turn signal switch	Refer to Lighting and Turn Signal Switch Inspection.
	Faulty BCM	Refer to Inspection of BCM and Its Circuits.
	Faulty LED DRL	Replace LED DRL.
Back up lights do not light up	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
	Blown bulbs	Replace bulbs.
	Faulty back up light switch	•M16A model: Refer to Back Up Light Switch Inspection:5 M/T. •D16AA model: Refer to Back Up Light Switch Inspection:D16AA-6M/T Model.
Brake lights do not light up	Faulty system circuit (including relay and fuses)	Repair circuit and replace relay and/or fuse.
	Blown bulbs	Replace bulbs.
	Faulty brake light switch	Refer to Brake Light Switch Inspection.
Turn signal / hazard warning lights do not flash	Faulty BCM	Refer to Inspection of BCM and Its Circuits.
	Faulty system circuit (including fuse)	Repair circuit and replace fuse.
	Blown bulbs	Replace bulbs.
	Faulty lighting and turn signal switch	Refer to Lighting and Turn Signal Switch Inspection.
	Faulty hazard warning switch	Refer to Hazard Warning Switch Inspection.