Recent GMC truck models shouldn’t drive down the road with only one headlight on, but many are. This single, winking look of these trucks comes from a simple electrical and design problem that seems obvious in hindsight. The new light-up badges proudly showcase the G-M-C lettering on the front grille, rendering half of the headlights on some trucks inoperable.

Are light-up badges a fad worth having?

LED lights, disappearing door handles, and integrated antennae are all vehicle developments that make the models we drive look much cooler than ever before. The same is true of the new GMC light-up badge. Unfortunately, this feature on the GMC trucks and SUVs is problematic.

Jalopnik tells us the GM Accessory Illuminated Emblem is a dealer-installed option costing between $310 and $475. That seems like a hefty price for illuminated lettering, but it might not be out of range in the grand scheme of things. Of course, if it causes problems, it could be more costly than the price of the badge.

What’s the problem with the GMC illuminated emblem?

Adding this feature to a GMC truck creates a weak link in the front-end lighting system. The wiring harness has a flawed design that could allow water to get to the connection and turn off the driver’s side headlight. Additionally, the turn signal could flicker or turn on by itself, leaving a driver with no way to signal their intention to turn.

Considering this happens when water enters the connection, it seems only logical to surmise the headlight shorting out occurs when driving in the rain, which creates a dangerous situation for everyone on the road.

Which GMC models are impacted by the faulty light-up badge?

GM Authority tells us the models affected by this problem include:

• 2020-2022 GMC Sierra 1500 and Sierra HD trucks
• 2021-2022 GMC Yukon and Yukon XL SUVs

If water or corrosion is found in the system, a GM technician will repair the headlights and clean the assembly and terminals. GMC has instructed technicians to bypass the light-up badge accessor to prevent further issues with this system. This is done by plugging the original headlight connector from the body harness back into the headlight assembly.

Unfortunately, if your GMC truck or SUV has this problem, you won’t have the cool light-up G-M-C letters on the front of your vehicle until a more permanent repair is available.

What if no water or corrosion is found in the electrical system?

When a GMC truck or SUV owner experiences some of the symptoms mentioned, but no water or corrosion is present in the electrical system, technicians are instructed to follow normal system diagnostic procedures. In these cases, if the Illuminated Emblem is present on the vehicle, the light-up badge will be disconnected as a safety precaution.

Light-up badge failure is dangerous, but it could be worse

Thankfully, the only affected parts of the GMC trucks and SUVs are one headlight and the turn signals. Considering how many electrical components are tied together in some vehicles, the situation could be much worse.

If you have a GMC vehicle that falls into the parameters of those impacted, it’s advisable that you contact your local dealer.  You may need to have the light-up badge disengaged until the permanent repair is found.