Buy GMC Terrain Tail Light Assembly

Overview

The tail light-also called a tail lamp, rear lamp, stop light or brake-light assembly-sits at the back of every GMC Terrain to let drivers behind you know when you are braking, turning, or backing up. On 2010-2017 models the outer lamp (mounted on the quarter-panel) and the inner lamp (mounted on the lift-gate) both use traditional 3057/3157 and 194 bulbs, while 2018-present Terrains switch to LED "C-shaped" signature lighting on every trim, making them brighter and faster-acting than filament bulbs.

Fitment Years

• 2010-2017 (First generation): Halogen tail lamps in two pieces-outer and inner-fit all SLE, SLT, and Denali trims. Denali adds chrome accents but keeps the same housings.
• 2018-2025 (Second generation): One-piece LED modules with a bold "C" light signature; brochure data shows LED tails standard across SLE, SLT, AT4, Elevation and Denali.
  Because of the redesign, first-gen and second-gen lamps do not interchange.

Key Features

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Safety Rules

Federal law (FMVSS 108) sets color, brightness, and placement for all replacement lamps. Tail lights must show red to the rear; backup lights must show white; turn signals may be red or amber. SAE J585 provides the laboratory tests that prove a lamp meets those rules. Always look for the "SAE" and "DOT" marks molded in the lens; they certify compliance.

Common Failures

• Cracked lens or broken tabs after minor bumps-common because the lamp sits flush with the body.
• Water inside the housing caused by aging seals; owners report condensation that can short bulbs or dull reflectors.
• Burned-out bulbs (first-gen only); the stop/turn filament runs hottest and usually fails first.
• Corroded sockets if moisture remains; check terminals for green or white powder.

Troubleshooting

1. Check the dash icon: If the BCM detects an open circuit it sets a "Rear Lamp Out" message.
2. Test the bulb: Swap a known-good 3157/194 bulb into the suspect socket.
3. Probe the connector: With ignition on, look for 12 V on the brown (tail) or yellow/green (stop/turn) wires. (JustAnswer)
4. Inspect the seal: Moisture inside means the shell must be resealed or replaced.

Replacement Steps

Time: 15 minutes per side (halogen) | Tools: 7 mm socket, trim tool, gloves

1. Open the lift-gate and pop off the two screw covers.
2. Remove the exposed 7 mm screws and pull the lamp straight rearward to unlatch the pegs.
3. Twist the bulb sockets counter-clockwise and lift them out.
4. Transfer bulbs to the new housing or install LEDs (observe polarity).
5. Align pins, push firmly until flush, then reinstall screws and covers.
   LED modules (2018-present) are bolt-on units with an internal harness; the procedure is the same but there are no bulbs to twist out.

Upgrade Ideas

• LED bulb kits for first-gen cars drop in to the 3157 socket and cut power draw by ~70 %.
• Smoked lenses can add style but must still show red light through them to stay legal-check for DOT marking.
• Sequential turn modules plug in-line and give a sweeping turn-signal effect; they do not affect brake function.

Maintenance Tips

• Wash lenses with car-shampoo, not household glass cleaner, to avoid micro-cracks.
• Rub a thin coat of plastic polish twice a year to block UV haze.
• Spray dielectric grease on bulb pins to slow down corrosion.
• After a rear-end repair, re-aim head-lamps and confirm tail-lamp fit to keep moisture out.

Compatibility

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Always match the eight-digit GM number on your old lamp when ordering.

Frequently Asked Questions

Q: What bulb size does my 2015 Terrain use?
A: The outer stop/turn uses a 3057 or 3157 dual-filament bulb; the inner tail lamp uses a 194 wedge bulb.

Q: Are 2018-2025 tail lights all LED?
A: Yes-GMC made LED tail lamps standard on every trim beginning with the 2018 redesign.

Q: Will a 2021 lamp fit my 2016 model?
A: No. The lamp shape, mounting points, and wiring changed completely for the second generation.

Q: How can I tell if a lamp is street-legal?
A: Look for "SAE (A, P, R)" codes plus "DOT" on the lens; that means it passed FMVSS 108 tests.

Q: What does the brown wire do?
A: Brown powers the running-light filament (tail). Yellow is left stop/turn, green is right stop/turn, black is ground. (JustAnswer)

Q: Do I need resistors if I swap to LED bulbs?
A: Only on 2010-2017 models; the BCM will hyper-flash unless you add a 6-ohm load resistor or use CAN-bus-ready LEDs.

Q: Where can I check for recalls?
A: Enter your VIN at the NHTSA recall lookup.

Q: Is water inside the lens covered by warranty?
A: If the vehicle is still under the 3-year/36 k basic warranty, yes; otherwise it's considered wear-and-tear unless an official campaign exists. Moisture issues are well documented by owners.

Q: Can I drive with a cracked tail lamp?
A: You'll pass most state inspections only if the red lens still covers the bulb and the light works; any white light leakage is grounds for failure.

Q: What torque for tail-lamp screws?
A: Hand-tight (≈ 27 in-lb). Over-tightening can crack the plastic boss.

Q: Why are LED lamps safer?
A: LEDs illuminate about 0.2 seconds faster than bulbs; that adds roughly a car length of extra reaction space for traffic behind you at highway speeds.

Q: Does tint film void legality?
A: If the red light output drops below SAE minimums it becomes illegal; always verify brightness after tinting.

Q: What is Partslink?
A: A cross-industry numbering system (e.g., GM2805105) that identifies replacement body parts regardless of brand.

Q: Are Terrain and Equinox tail lamps the same?
A: For many 2010-2017 models they share housings but differ in lens styling; part numbers are unique, so buy Terrain-specific lamps.

Q: How long do LEDs last?
A: Rated 30 000-50 000 hours-often outliving the vehicle.

Q: Can I retrofit sequential LEDs into the stock housing?
A: Yes, kits replace the bulb and add an in-line flasher module; they require no splicing on first-gen cars.

Q: What fuse protects the tail lamps?
A: Check the rear fuse block, fuse F26 (tail). Consult your owner's manual for the exact slot.

Q: Does towing affect tail-lamp wiring?
A: Use a powered trailer module; splicing directly into the Terrain's wires can trigger bulb-out warnings.

Helpful References

• FMVSS 108 full text
• SAE J585 tail-lamp test standard
• GMC 2024 Terrain brochure (PDF)
• Owner's Manual bulb-change pages
• GMC Life: lighting design overview

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