What Is A High Mount Lamp Assembly And Why Is It Important?

On all newer vehicles, you'll see a brake light above the rear window. That's called a high mount lamp. In this post, we'll talk about what this part is and why it's important.

What Is A High Mount Lamp Assembly?

Do you see a third brake light above your rear window or deck lid? That's the high mount lamp assembly. It's a part of your vehicle's brake light system.

There are several other names for this part, including:

  • High mount stop light assembly
  • High mounted stop lamp
  • Third brake light assembly
  • Center high mount stop lamp assembly
  • Cyclops brake light

For the sake of clarity, we'll refer to this part as a "high mount lamp assembly" in this post.

A high mount lamp assembly is a lamp that's affixed to the top of the rear window. It lights up when you hit the brakes, along with the two brake lights on the rear of the vehicle. The lamp is red in color, like the other brake lights on the vehicle.

The Components Of A High Mount Lamp Assembly

high mount light parts

A standard high mount lamp assembly is a straightforward part. It sports a simple design. The set of components of a high mount lamp assembly depends on your GM model. For example, the high mount lamp assembly on 2002-2006 Cadillac Escalades has only a few parts:

  • Light bulb
  • Plastic housing
  • Wires
  • Connector

Why Is It Important To Have A Functioning High Mount Lamp Assembly On Your GMC Vehicle?

No one really knows how the high mount lamp assembly was invented. There are a couple of theories:

  1. In 1973, a San Francisco cab driver was frustrated by being rear-ended all the time. He addressed the issue by hard-wiring a third brake light in his rear window. Legend has it that he never got rear-ended again.
  2. In 1974, a psychologist wanted to see if a third brake light would reduce rear-end collisions. He put a third brake light on over 300 taxicabs. He left 160 taxicabs without a third brake light. His experiment lasted 10 months. As a result, the taxicabs with the third brake light experienced 60.6% less rear-end collisions than the taxicabs without.

It's possible that both theories are correct. The psychologist may have gotten the idea from the cab driver. In 1986, the US government mandated all vehicles to have a high mount lamp assembly. They felt confident that a brake light placed higher and more prominently would help prevent rear-end accidents.

A Functioning High Mount Lamp Assembly Reduces Rear-End Collisions

Rear end collision

With a high mount lamp assembly on every car, rear-end collisions become less common. Many different studies confirm that third brake lights reduce the likelihood of accidents. Since the introduction of high mount lamp assemblies on all cars, the US has seen:

  • 200K fewer crashes every year
  • 60K fewer injuries every year
  • At least $600 million in property damage saved every year

A high mount lamp assembly works so well because it:

  • Increases visibility
  • Still works when one of the other brake lights go out
  • Provides an extra warning signal to distracted drivers
  • Helps other drivers tell the difference between a brake light and a turn signal

Replacing Your OEM High Mount Lamp Assembly

OEM GM high mount lamp assemblies usually last the lifetime of the vehicle. Sometimes they will fail early. When that happens, you can replace it at home. We carry genuine OEM GM parts, including high mount lamp assemblies. We offer the lowest transaction prices you'll find online. That means you'll save a lot of money by shopping with us! Look up your GM model here to see if we have a replacement high mount lamp assembly for your car.