2021 GMC Sierra 1500 Bulb Size Guide

Quick Reference

The 2021 GMC Sierra 1500 offers a mix of traditional halogen and advanced LED lighting, with the specific bulb type often depending on the trim level. Base models typically feature halogen bulbs for most exterior lighting, while higher trims like the Denali, AT4, and SLT often come equipped with full LED headlamps, fog lights, and DRLs from the factory.

For low beam, high beam, and fog lights, if your Sierra 1500 is not equipped with the factory LED lighting package, you'll find H11 bulbs for both low beams and fog lights, and H7 for high beams. These are common halogen sizes, making upgrades straightforward. The DRLs on halogen-equipped models typically use a W21W bulb. Front turn signals are often a 7443NA halogen bulb, though some higher trims might have LED front turn signals integrated into the headlamp assembly. Rear turn signals and brake lights commonly use a 3157 halogen bulb. Reverse lights are usually a 921 halogen bulb, and license plate lights and interior dome/map lights utilize the versatile 194 bulb. It is important to note that many tail light functions on the 2021 Sierra 1500, especially the main tail light and rear side markers, are integrated LED units that are not designed for individual bulb replacement.

LED vs Halogen Upgrade Considerations

Upgrading your 2021 GMC Sierra 1500's halogen bulbs to LED can significantly improve visibility and modernize the vehicle's appearance. However, there are a few key considerations to keep in mind:

CANBUS Errors: Modern vehicles like the Sierra 1500 utilize a CANBUS (Controller Area Network Bus) system to monitor electrical components, including lighting. LED bulbs draw significantly less power than their halogen counterparts, which can sometimes trick the CANBUS system into thinking a bulb is out. This can trigger