What Size Bulbs Does a 2018 GMC Terrain Use?
Correct headlight, fog light, and tail light bulb sizes. Sourced from OEM catalog data.
Installation Difficulty
Moderate (Dust covers often present)
Est. Replacement Cost
$15 - $40 (Halogen) / $30+ (LED)
What Lighting System Does the 2018 GMC Terrain Have?
The 2018 GMC Terrain features an extensive lighting system with 11 bulb positions. It uses halogen technology with a single HID-D5S LED dual-filament bulb handling both low and high beams. The Terrain has been available from 2010 to 2019, and the 2018 model falls in the late-generation years.
Can You Put LED Bulbs in a 2018 GMC Terrain?
Upgrading the 2018 GMC Terrain to LED headlights is straightforward since it uses a single HID-D5S LED dual-filament bulb for both low and high beams. You only need one pair of LED bulbs to upgrade both functions. Look for a HID-D5S LED LED kit that specifically supports dual-filament operation to ensure both beams work correctly. For the fog lights, a H11 LED LED bulb provides a clean white output that pairs well with LED headlights.
How to Replace Bulbs on a 2018 GMC Terrain
To remove the headlight bulb, disconnect the wiring harness, then twist the bulb counter-clockwise and pull it straight out of the housing. On the 2018 Terrain, you will likely encounter rubber dust covers behind the headlight housing. These pull off by hand or unscrew depending on the design. Allow about 15 to 20 minutes per side. When installing the new bulb, avoid touching the glass with bare fingers. Skin oils create hot spots that shorten bulb life. Wear clean gloves or handle the bulb by its plastic base only. The fog lights are accessed from underneath the front bumper. You may need to remove a few plastic clips or screws from the fender liner to reach the H11 LED fog light socket.
Full Upgrade Bundle
Upgrade All 11 Positions at Once
2018 GMC Terrain Complete Bulb Size Chart
| Position | Bulb Size | Shop |
|---|---|---|
Low Beam | HID-D5S LED | Buy HID-D5S LED |
High Beam | HID-D5S LED | Buy HID-D5S LED |
Fog Light | H11 LED | Buy H11 LED |
Brake Light | LED Bulb | Buy LED Bulb |
Turn Signal Front | 7444NA | Buy 7444NA |
Side Marker | LED Bulb | Buy LED Bulb |
Turn Signal Rear | 7440 LED | Buy 7440 LED |
Reverse Light | 921 | Buy 921 |
License Plate | 2825 | Buy 2825 |
Parking Light | 7444NA | Buy 7444NA |
Trunk Light | LED Light | Buy LED Light |
Want to upgrade everything at once?
Shop Complete LED Kit for 2018 GMC TerrainHow Long Do 2018 GMC Terrain Headlight Bulbs Last?
Standard halogen headlights on the 2018 GMC Terrain have an expected lifespan of 500 to 1,000 hours, which works out to roughly 2 to 3 years of normal use. Signs of a failing halogen bulb include noticeably dimmer output, a yellowish tint compared to the other headlight, or intermittent flickering. At 8 years old, the original bulbs on your Terrain are likely overdue for replacement. Even if they still illuminate, reduced brightness significantly impacts nighttime safety. When one headlight burns out, replace both sides at the same time. Bulbs from the same batch age at similar rates, and mismatched brightness is distracting to oncoming drivers.
What Bulbs Are Compatible with the 2018 GMC Terrain?
The D5S low beam bulb on the 2018 GMC Terrain is a specific fitment. There are no widely recognized cross-compatible alternatives, so make sure to purchase the exact D5S size. Using the wrong bulb size can cause improper beam patterns that reduce your visibility and blind other drivers. It can also cause overheating inside the headlight housing, potentially warping the plastic lens or reflector. Always verify the bulb number before purchasing.
2018 GMC Terrain Headlight FAQ
Did GMC Terrain Bulb Sizes Change Over the Years?
Over its production run from 2010 to 2019, the GMC Terrain has seen bulb size changes in the Low Beam, High Beam and Fog Light positions. The 2018 model uses the newer bulb specification introduced around 2018. Always verify the exact bulb size for your specific 2018 model year using the chart above, as using the wrong size can result in poor fitment or reduced light output.
Other Terrain Years
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Other Vehicles That Use HID-D5S LED Bulbs
These vehicles from other makes also use a HID-D5S LED low beam bulb: