Buy Ford Focus Tail Light Assembly

Quick Summary

The Ford Focus tail light-also called a rear lamp, tail lamp, rear light, or stop light-keeps you visible and safe. It houses red running lamps, brighter brake lamps, amber or red turn-signals, and white reverse lights. Focus models from 2000-2018 share the same basic job, but shapes, bulb types, and wiring change by generation. Federal rules (FMVSS 108) tell builders where the lamp must sit and how bright it must shine. Common issues include burned-out 3157/P21-5W bulbs, blown fuses, moisture, and cracks. Most owners can swap a bulb or even the whole assembly with hand tools in under 15 minutes. Upgrading to LEDs cuts power use and lights up faster, while keeping the car street-legal if you choose DOT-approved parts.

Part Basics

A tail light assembly sits on the rear corners and lets drivers behind you see and understand your moves. It combines running, brake, turn-signal, and backup functions in one piece. Those signals reduce rear-end crashes by warning others early. LED versions glow brighter and faster than old-style incandescent bulbs, and they last much longer.

Model Years

• 1st Gen (2000-2007 US) - tall, two-piece lamp on sedans and coupes. (Wikipedia)
• 2nd Gen (2008-2011) - slimmer sedan lamp with clear upper section for reverse lights. (Wikipedia)
• 3rd Gen (2012-2018) - wrap-around hatch and sedan lamps; some trims offer factory LEDs. (Wikipedia)
• 4th Gen (2019-on, mostly outside N. America) - reshaped LED units; U.S. production ended after 2018. (Wikipedia)

Key Functions

• Tail / Parking light - low-intensity red LEDs or bulbs that stay on with the headlights.
• Stop light (brake lamp) - bright red when you press the pedal. Instant-on LEDs shave milliseconds off reaction time.
• Turn signal - flashes amber (EU) or red (US) from the same housing.
• Reverse light - clear or white to light up when backing.

Bulb & LED Choices

• Most 2012-2018 U.S. cars use dual-filament 3157 (also labeled P21/5W) incandescent bulbs for run/stop and single-filament 7440/7443 for turn signals.
• LED retrofit bulbs draw about 75 % less power and can last 10-plus years.
• Some aftermarket assemblies replace every bulb with built-in LED boards; one example lists overall size (18 × 14 × 27 in) so you can confirm fit before buying.

Materials

Most Focus rear lamp lenses are made from impact-resistant polycarbonate plastic, the same tough material used on headlamps. It resists shattering but can yellow from UV unless you wax or coat it.

Legal Rules

The U.S. Federal Motor Vehicle Safety Standard 108 sets brightness, color, activation, and mounting-height limits for replacement lamps (49 CFR 571.108).
Upgrades that keep red output and original reflector positions usually stay compliant. Always avoid tinted lenses so dark that they cut light below the DOT minimum.

Common Problems

• Burned bulbs - one side dark or dim; dash may show "Brake lamp bulb fault."
• Blown fuse - no tail or brake lamps at all; check interior fuse panel positions F7/F20, depending on year.
• Condensation / water - brief fog is normal, but standing water points to a crack or failed seal.
• Recall-level cracks - Ford has recalled some vehicles for microscopic cracks that disable reverse lamps.

Diagnosis Steps

1. Switch on headlights; check both rear corners.
2. Have a helper press the brake; watch for brighter red.
3. If dark, pull the 3157 bulb and inspect the filaments.
4. Still dark? Inspect the fuse box in the glove-box area (see interactive diagrams at StartMyCar). (link)
5. Moisture inside? Look for hair-line cracks; dry the housing with a hair dryer, then reseal with automotive silicone.

DIY Replacement

An online repair guide shows the whole job on a 2014 Focus:

• Open the trunk and remove two plastic wing-nuts.
• Pull the lamp straight back; no prying.
• Twist the bulb socket counter-clockwise, swap the bulb, and re-install.
  Most owners finish in under 15 minutes with only a 10 mm socket and gloves.

Upgrade Ideas

• Full LED assemblies give a modern look and quick response. They also reduce alternator load.
• Sequential turn signals add style as long as the kit is SAE/DOT marked.
• Smoke or clear lenses are legal only if red output and reflector remain clearly visible.

Care Tips

• Wash lenses with mild car soap; avoid glass polish that can scratch plastic.
• Apply a UV-blocking wax twice a year to slow yellowing.
• After snow or heavy rain, pop the trunk and wipe seals to stop water pooling.

Frequently Asked Questions

Q: How do I know which tail light fits my Focus?
A: Match the body style (hatch or sedan) and model year. The 2012-2014 lamps differ from 2015-2018 because of a facelift. (Wikipedia)

Q: What bulb number is standard?
A: Most U.S. third-gen cars use dual-filament 3157 (a.k.a. P21/5W) for the run/stop section.

Q: My dash says "Brake lamp bulb fault" but the lights work. Why?
A: A high-resistance socket can trigger the warning even when the bulb glows; clean the contacts or replace the socket.

Q: Are LEDs legal?
A: Yes, if the assembly is DOT-approved and emits the same red/amber colors at required brightness. FMVSS 108 applies to all replacements.

Q: Where is the tail-light fuse?
A: On most 2012-2014 cars it sits in the passenger-footwell panel (Fuse F7 or F20; check your diagram).

Q: Why is there mist inside the lens after a car wash?
A: Warm air inside meets cold outer plastic and forms condensation; it usually clears in minutes. Standing water means a leak.

Q: What recalls cover rear lamps?
A: A 2023 Ford notice covered cracking rear light-bars that could disable reversing lights. Dealers replace them free.

Q: Can I repair a cracked lens?
A: Small cracks can be sealed with clear epoxy, but deep damage lets dirt in and replacement is safer.

Q: Do smoked covers affect brightness?
A: Yes-dark tint reduces lumen output. If the red light is too dim, it can fail inspection or cause a ticket.

Q: How long do LED tail lights last?
A: Quality LEDs often last 25,000-50,000 hours-many times the life of a filament bulb.

Q: Are tail-light lenses glass or plastic?
A: They are nearly always polycarbonate plastic because it is lighter and almost shatter-proof.

Q: My lamp keeps fogging; is that normal?
A: A light fog is normal; if droplets grow or stay, you may have a vent or seal issue.

With these facts, specs, and tips, you're ready to pick, install, and care for any Ford Focus tail light and keep your compact safe and bright on the road.