Why Hyperflash Happens — And How We Work to Prevent It

You install a new set of LED headlights or taillights, turn on the signal, and suddenly the blinker starts flashing twice as fast as normal.

That's hyperflash.

But why does it happen—and what do we do at CraftC Performance to help prevent it?

What Causes Hyperflash?

Most vehicles are designed to monitor the electrical load of the turn signal circuit.

Traditional halogen bulbs draw significantly more power than LEDs. When an LED light replaces the factory lighting, the vehicle may detect a lower electrical load than it expects.

To the vehicle, that can look like a failed or burned-out bulb.

The result?

Hyperflash.

Instead of flashing at the normal speed, the turn signal begins blinking rapidly to alert the driver that something may be wrong with the lighting circuit.

The LED itself isn't necessarily defective. In many cases, the vehicle simply isn't seeing the electrical behavior it expects.

So How Do We Prevent It?

This is why developing aftermarket lighting involves much more than making an LED illuminate.

At CraftC, electrical compatibility is part of the development process from the beginning.

01 — Study the Factory System

Before finalizing a lighting system, we look at how the original vehicle handles its turn signals, DRLs, brake lights, and other lighting functions.

Different model years and trims can behave differently—even when the lights look nearly identical from the outside.

Understanding the factory system gives us the baseline we need to design around.

02 — Develop the Harness & Electronics

The next step is making the aftermarket lighting communicate properly with the vehicle.

Depending on the application, this can involve:

• Vehicle-specific wiring harnesses

• Load resistors

• Decoders

• Control modules

• Correct connector and pin configurations

• Proper electrical load matching

These components help reproduce the electrical characteristics the vehicle expects to see.

The goal is simple:

Upgrade the lighting without making the vehicle think something is wrong.

03 — Test More Than Just “Does It Blink?”

A turn signal working once in the shop isn't enough.

During development, we test different lighting conditions and vehicle functions.

For example:

Vehicle started → Turn signal on

DRLs on → Turn signal

Parking lights on → Turn signal

Headlights on → Turn signal

Hazards activated

We also check both the driver and passenger sides and monitor whether the behavior changes depending on which other lighting functions are active.

Why?

Because modern vehicle lighting systems interact with each other.

A setup that behaves normally with the headlights on can sometimes behave differently with the DRLs or exterior lighting switched off.

That's exactly why real-vehicle testing matters.

04 — Test on Different Vehicles and Trims

One of the biggest challenges with aftermarket lighting is variation.

Two vehicles from the same generation may have differences in:

• Model year

• Trim level

• Factory lighting package

• Wiring configuration

• Control modules

• Electrical behavior

That's why we don't want development to stop with a single test car whenever additional configurations need to be verified.

We use real vehicles and feedback from testers to identify differences before and after a product reaches production.

05 — Validate the Complete Lighting System

We don't only test one component in isolation.

Whenever possible, we evaluate how the lighting system behaves together.

That becomes especially important when a vehicle has aftermarket:

Headlights + Taillights

Both products can change the electrical load seen by the vehicle.

The combination therefore needs to be considered—not just each light individually.

06 — Heat Matters Too

A resistor can generate heat while it is doing its job.

That means simply adding resistance isn't enough.

Its specification, placement, wiring, and surrounding materials all matter.

Part of proper development is making sure the solution isn't only electrically functional but also appropriate for long-term operation.

What Happens If We Still Find Hyperflash?

Real-world vehicles can reveal combinations that don't appear during initial development.

When that happens, we don't automatically assume the entire light is defective.

We troubleshoot the system.

Our process may include checking:

1. Vehicle year, make, model, and trim

2. Whether the issue affects one or both sides

3. Whether hyperflash occurs with DRLs, parking lights, or headlights on/off

4. Factory and aftermarket lighting currently installed

5. Harness and connector installation

6. Resistor or decoder configuration

7. Video of the vehicle's actual behavior

That information helps us identify whether the issue is coming from installation, vehicle configuration, electrical load, or the product itself.

And when we discover something that can be improved, that information goes back into product development.

Test. Learn. Improve.

For us, product development doesn't stop when the first production batch leaves the factory.

Real customers put products into environments that are difficult to completely recreate during development.

Different trims.

Different modifications.

Different climates.

Different combinations of aftermarket components.

That feedback matters.

When we identify a repeatable issue, our goal is to understand why it happens, develop a solution, validate it, and carry what we learn into future production.

That's part of how CraftC products continue evolving.

More Than Making the LEDs Turn On

Building automotive lighting isn't simply about designing something that looks good.

The product has to work with the vehicle behind it.

Housing.

Optics.

Connectors.

Wiring.

Electrical load.

Vehicle electronics.

All of those pieces have to work together.

That's why we test beyond appearance.

Because lighting shouldn't just fit the car—it should work with it.

CraftC Performance
Lighting designed for the car. Not just made to fit it.