Why Do GMC Trucks Have Such Terrible Headlights?

For such a big, rugged truck, the GMC Sierra has some of the worst headlights on the road. But why?

GMC Sierra owners are seeing red. Well, technically they’re not seeing anything. That’s the problem.

The headlights in the 3rd generation (2014–present) are so dim, you’d probably get better illumination from a jar of fireflies taped to the bumper. GMC changed the design for 2016, leaving owners of previous model years wondering if they’ll be left in the dark?

GM Changed Their Headlight Design for 2014

In prior model years, GM used three different bulbs for the Sierra’s headlights — a H11LL bulb for the low beams, a 9005LL bulb for the high beams and a 5202 bulb for the fog lights.

But starting with the 2014 model year, GM switches to one 9012 halogen single filament bulb for both the low and high beams. Historically, automakers have at least used dual-filament bulbs for low / high beams.

“The headlights are terrible, low beams are absolutely useless and high beams are only slightly better.”

For 2016, GM “refreshed” the Sierra design with a new grille, front fascia and yep … headlight design.

Common Complaints About the Sierra Headlights

  • Driving at night, especially in the rain, can feel very dangerous
  • The light output and beam pattern are both terrible, providing very little lateral illumination
  • The design uses a single (crappy) projector for both low and high beams, with just a shutter that raises for high beam.
  • $40-50k trucks shouldn’t come with budget headlights

Not a Bright Sight

IIHS Says News Truck Headlights Are Terrible

Turns out it’s not just the Sierra, because according to the IIHS pretty much all new truck headlights are terrible. In fact, the more expensive the truck the worse the stock lights.

The Institute tested headlights on small and large 2016-2017 pickups and found the most expensive trucks are the vehicles that come equipped with the poorest headlights. And out of the four small pickups and seven large pickups tested, only one truck achieved a “good” rating for the headlights.

The 2016 and 2017 Sierra earned “acceptable” ratings. That seems a little optimistic.

GM Issued Instructions to Dealers on How to Fix the Problem

On March 1st, 2015, GM released TSB #PIT5374 to its dealers titled Headlight Performance (BCM Calibration and Bulbs). Technical service bulletins (TSBs) are a set of instructions on automaker sends to its dealers about how to handle specific problems.

Here’s how it starts:

Some customers may comment of poor headlight performance when driving in very dark rural areas. While the headlights meet all Federal Motor Vehicle Safety Standard (FMVSS) requirements and Canada Motor Vehicle Safety Standard (CMVSS) requirements, customers may request better headlight performance for these very dark rural areas.

OK, two things here:

  1. Aren’t very dark rural areas where you need dependable headlights the most? Mentioning this twice seems odd.
  2. Know your target market. Farmers and blue-collar workers — who hey, by the way, live in these “very dark rural areas” — are one of the biggest buying groups for your trucks.

The TSB goes on to make the following recommendations once the headlights have been diagnosed to be working properly:

  1. For vehicles built before 12/23/14 at Flint Assembly (11th VIN digit “F”), 1/13/15 at Silao Assembly (11th VIN digit “G”), or 1/1/6/15 at Ft. Wayne Assembly (11th VIN digit “Z”), reprogram the BCM with the latest calibration available in TISWEB starting on 1/1/2/15. The new BCM calibration will increase the voltage to the headlight bulbs in both low and high beam selections.

The BCM is the body control module and its a generic term for a control unti that monitors and controls electronic accessories, like the headlights, on a vehicle. The TSB says that vehicles built after the referenced dates already get the increased voltage.

  1. Replace both headlight bulbs with updated bulb part number 23342527 … After bulb replacement, perform Headlamp Aiming Procedure.

Ah, ha! New headlights made by Vosla. Now we’re starting to see the light.

There Are Still Class-Action Lawsuits About the Headlights

In late 2015 a class-action lawsuit was filed claiming Sierra 1500 owners can’t drive at night because of the defective headlights. The lawsuit points to GM’s TSBs and the recent redesign as evidence that GM knows how bad this problem really is.

“Brand new GMC Sierra truck that I am afraid to drive an night. First thought that my eyes suddenly were falling apart or my windshield was tinted, but these headlights are the worst I have ever seen (or more correctly, not seen) on a vehicle.”

“I have owned eleven vehicles in my lifetime and these are the worst headlights I have experienced. A very short cutoff and worst of all, no side illumination. — 2014 Sierra 1500 owner

But General Motors Wants Them Dropped

GM wants the charges against them dropped and it’s not because they’re standing behind their product. The main points of GM’s argument are all legal hurdles:

  1. None of the lawsuits are claiming the lights are malfunctioning in any way
  2. The lawsuits talk about how the dim lights will lead to more nighttime accidents without showing any data to back it up
  3. The plaintiffs aren’t accusing GM of making any inaccurate statements about the brightness of the lights

For now, the case remains open in a California

Vehicles That Might Have This Problem

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