Safety Warning

DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.

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HOMESERVICE MANUALSTOYOTA2004CELICA GT, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 249 (BODY ELECTRICAL SYSTEMS (TROUBLESHOOTING))TROUBLESHOOTINGPROBLEM SYMPTOMSHEADLIGHT AND TAILLIGHT SYSTEM (W/O DRL)

2004 Toyota Celica GT, Standard

Headlight And Taillight System (W/O DRL)

2004 Toyota Celica GT, StandardSECTION Headlight And Taillight System (W/O DRL)

WARNING: This page is about a different car, the 2002 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.

This system uses the multiplex communication system, so check diagnosis system of the multiplex communication system before you proceed with troubleshooting.

HEADLIGHT SYSTEM (W/O DRL)

Symptom/Suspect Area

See

Only One Headlight Comes On

Bulb

.....

Wire Harness

.....

"Lo-Beam" Does Not Light (All)

Headlight Control Relay

⁽¹⁾

Headlight Dimmer Switch

.....

Wire Harness

.....

"Lo-Beam" Does Not Light (One Side)

Bulb

.....

H-LP LH Fuse

⁽²⁾

H-LP RH Fuse

⁽²⁾

Wire Harness

.....

"Hi-Beam" Does Not Light (All)

Headlight Control Relay

⁽¹⁾

Headlight Dimmer Switch

⁽³⁾

Wire Harness

.....

"Hi-Beam" Does Not Light (One Side)

Bulb

.....

H-LP LH Fuse

⁽²⁾

H-LP RH Fuse

⁽²⁾

Wire Harness

.....

"Flash" Does Not Light

H-LP LH Fuse

⁽²⁾

H-LP RH Fuse

⁽²⁾

Bulb

.....

Headlight Dimmer Switch

⁽³⁾

Body ECU

⁽⁴⁾

Wire Harness

.....

Headlight Does Not Come On

Bulb

.....

Headlight Control Relay

⁽¹⁾

Light Control Switch

⁽⁵⁾

Body ECU

⁽⁴⁾

Wire Harness

.....

Headlight Flickers

Bulb

.....

Body ECU

⁽⁴⁾

Wire Harness

.....

Headlight Is Dark

Bulb

.....

Body ECU

⁽⁴⁾

Wire Harness

.....

Only One Tailight Comes On

Bulb

.....

Wire Harness

.....

Tailight Does Not Come On (Headlight Is Normal)

Tail Fuse

⁽²⁾

Taillight Control Relay

⁽⁶⁾

Light Control Switch

⁽⁵⁾

Wire Harness

.....

Tailight Does Not Come On (Headlight Does Not Light)

Light Control Switch

⁽⁵⁾

Wire Harness

.....

Rear Combination Light Does Not Come On

Bulb

.....

Wire Harness

.....

⁽¹⁾	INSPECT HEADLIGHT CONTROL RELAY CONTINUITY

⁽²⁾	FUSES & CIRCUIT BREAKERS

⁽³⁾	INSPECT HEADLIGHT DIMMER SWITCH CONTINUITY

⁽⁴⁾	HOW TO PROCEED WITH TROUBLESHOOTING

⁽⁵⁾	INSPECT LIGHT CONTROL SWITCH CONTINUITY

⁽⁶⁾	INSPECT TAILLIGHT CONTROL RELAY CONTINUITY

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.
• Brakes feel soft, pull hard to one side, or make grinding noises.
• The engine overheats, stalls repeatedly, or misfires under load.
• You are missing required tools, torque specs, or safe lifting equipment.
• You are not confident in the next step or safety outcome.