No Flasher Relay to Replace? LED Turn Signals on CAN-bus and Computer-Controlled Motorcycles

On a lot of motorcycles, the part that makes your turn signals blink is a small plug-in flasher relay you can pull out and replace. On some of the newer bikes, that part is gone. The flasher relay function is built into the motorcycle's computer (the ECU or body control module) and controlled by software, so there is nothing to unplug and swap. This guide is for those bikes: what actually goes wrong when you install LED blinker lamps, why the fast blink and the dash warning light are the same problem and not two, and how to fix it.

One problem, not two: why the blink speeds up and the dash lights up together

Here is the part the internet usually gets wrong. On a computer-controlled bike, the same circuit that flashes your turn signals is also watching that circuit to decide whether a lamp has burned out. It judges that by how much current the circuit draws. A stock incandescent blinker lamp pulls a known amount of current; an LED blinker lamp pulls a fraction of it.

When the computer sees that low draw, it concludes the lamp has failed, and it reacts in two visible ways at once: it speeds up the blink (the classic hyperflash) and it puts a bulb-out warning in the gauge cluster. These are not two separate faults with two separate fixes. They are one judgment by the computer, that the circuit looks wrong, shown to you two ways. Address the cause and both clear together.

This can also happen on newer motorcycles that come with LED blinker lamps from the factory, as most aftermarket LED blinker lamps consume less power than the OEM. The motorcycle's ECU/BCM is tuned specifically for the power consumption of the OEM blinker lamps, and even a small variance can trigger the lamp error.

The fix: give the circuit back the load it expects

Since the computer is reacting to low current, the fix is to add the current back. A load equalizer is a power resistor that wires in parallel with your LED blinker lamp and draws the same amount of current the original incandescent lamp did. With the stock load restored, the computer sees a normal circuit again, the blink rate returns to normal, and the bulb-out warning goes away, because you have addressed the one thing that was triggering both.

One caveat before you buy: load equalizers are the fix for the large majority of bikes with no replaceable flasher relay, but not all of them. If your bike uses a constant-current system, adding load will not work and no load equalizer will solve it, so it is worth ruling that out first. We explain how to spot it in the constant-current section below.

Two rules make this work:

• Match the wattage of the original blinker lamp you removed. Too little load and the system still reads bulb-out, so the fast blink stays. We make them in 2 watt, 10 watt, 25 watt, and 25 watt heavy-duty sizes so you can match the bike.
• One load equalizer per converted blinker lamp - typically four for a full LED swap, front and rear on both sides. They are sold as pairs.

Load Equalizer - 2 Watt (pair) The smallest size. Right when the blinker lamp you removed drew very little, such as a factory low-wattage or already-LED circuit. Two watts on its own often still reads as bulb-out on an incandescent bike, so match your removed bulb wattage.

Load Equalizer - 10 Watt (pair) A middle size for lower-wattage OEM blinker lamps. Match it to the wattage of the lamp you removed.

Load Equalizer - 25 Watt (pair) The common choice for restoring a normal blink on bikes that ran standard incandescent blinker lamps. It mimics a 20 to 30 watt bulb so the computer sees a normal circuit.

Load Equalizer - 25 Watt Heavy Duty (pair) The same 25 watt load with extra thermal headroom for hotter installs or tight spaces. Use it when a standard 25 watt unit runs too hot.

For how to size them and the electrical background, see our guide to LED load equalizers.

How to tell whether your bike even has a replaceable relay

Before you buy anything, confirm which kind of bike you have. The quick field test: locate the suspected flasher relay, often under the seat or near the fuse box, and unplug it. If your turn signals stop working entirely, it was the flasher relay, and on a relay bike swapping in an electronic LED flasher relay is the cleaner fix. If the signals still work with that part unplugged, it was a power relay, not the flasher, which means the flasher function is integrated into the computer, there is nothing to replace, and load equalizers are your path.

If your bike does have a replaceable relay, this is the wrong guide. Start with our guide to LED flasher relays instead, and browse the Electronic LED Flasher Relays that fit it.

The exception: constant-current systems, where adding load will not work

Some recent models drive their blinker lamps with a constant-current design rather than a standard 12 volt circuit. The voltage on these systems will float within a range, to achieve the specified current output to drive the OEM blinker lamps. Typically these systems will measure at a lower voltage, like 7-9V when operating. There is no way to connect an aftermarket blinker lamp designed for constant voltage (12V nominal) to this system and have it function properly. You will certainly be stuck in the fast-blink lamp warning mode, and your aftermarket lamps will never see the 12V they were designed for.

These systems are hard to detect without taking direct measurements of voltage. We have designed our Blaster-X Tail Lights to work properly on motorcycles equipped with these systems (like the 2015+ Yamaha Road Star Raider), but there is currently no blinker converter for the front.

A note on what the CANbus Load Equalizer is, and is not

We do sell a product called the CANbus Load Equalizer, but it is a brake-circuit part that restores cruise-control function and clears bulb-out messages on certain late-model Harley and Victory tail-light installs. It is not the part for turn-signal fast blink. For blinker hyperflash, the fix is the standard wattage-matched Load Equalizers above. It is designed to pair with the Universal Magic Strobes Brake Light Flasher, and it works whether that modulator is wired inline on the brake circuit or as part of an OEM tail-light replacement; we have tested it on late-model Harley and Victory.

Related reading

• Sizing and electrical background: our guide to LED load equalizers.
• For bikes that do have a replaceable relay: our guide to LED flasher relays.
• If all four signals flash together: our 4-way blink guide.