Honda Grom LED Headlight/turn signal conversion

Here's how I converted a 2015 Honda Grom's stock headlight...

Into a classier LED setup:

As part of the build, I also put in MotoPower 3.1Amp Waterproof USB charger to power a cell phone or GPS, and a switch to turn the headlight on and off.

To begin I disconnected the battery, removed the old headlight/signals, and removed the side panels for access.


With everything taken apart, my next step was sorting out power for the new headlight.

In the stock setup, the headlight gets power from a yellow wire coming from this regulator located behind the rear brake cylinder.

Looking at the wiring diagram, we can trace the yellow wire over to the dimmer switch on the handlebars, which then feeds the power via a blue and white wire to the headlight.

The power from the regulator originates from the alternator and is Alternating Current, which won't work for the new LED headlight that needs Direct Current.

Rather than purchase a converter, I piggy-backed off the 12v DC power that runs to the tail light.

So the plan was to de-pin the yellow wire going into the regulator, and extend it to tap into the tail light wire.

To do this, I pulled out the regulator and unplugged its harness, and from the harness, I de-pinned the yellow headlight wire.

Next, I moved to the tail light wiring harness located up and to the left of where the regulator sits. The black wire going into this harness is what sends power to the tail light.

To test things out, I temporarily ran a connection from the black tail light wire's port, down to the yellow headlight wire.

Then I plugged in my new LED light to the existing plug the stock light was plugged into. After re-connecting the battery and turning on the bike, the headlight turned on as planned.

Next, I wanted to plan a switch to be able to turn off the headlight when the bike was on. The switch required a ground wire which I ran from the grounding bolt behind the gas tank.

Now that all my tests were complete, I moved on to properly running the wires.

Running wires

Near the front of the bike, you can see where I ran a (1) power, (2) ground and (3) headlight wire. These all run back toward the seat area via an old bike tube tucked behind the frame.

I tapped in a second connection to the power and ground to run a connection to the USB plug.

If we trace the red power wire back it runs through the tube which gets tucked behind the frame...

...and here you can see where it was tapped into the black power wire.

Similarly, the black ground wire runs through the tube, then up to the grounding bolt.

Finally, I ran some yellow wire back through the tube and soldered it to the yellow headlight wire I had de-pinned earlier.

It would be more ideal to have this switch up near the grips, but I didn't want to deal with running wire that would have to pivot with the handlebars. It's not a switch I'll need to use frequently, so I think this location is adequate.

Headlight brackets

At this point the wiring was done so I moved on to working on the headlight and turn signals.

I mocked up some brackets using a paper template. From this template I cut out some wood prototypes to make sure everything lined up and would hold the headlight properly.

Using the wood prototypes as a template, I cut out some metal brackets a sheet of 16 gauge steel.

I could have painted these brackets black and called it a day, but I wanted to cover some of the gap behind the headlight and the gauge box. To accomplish this, I cut out some covers from .080" thick ABS plastic to go over the bracket. Using a heat gun, I bent the plastic into shape to curve into the instrument gauge.

Even though the metal brackets are going to be covered by the plastic, I decided to paint them black to test out with a new powder coating system I had picked up.

While I had the powder coater out, I also covered the bolts, washers and spacers that fix. the brackets and light to the bike.

Turn signals

Next step was turn signals. The LED headlight I'm using (7" LED Daymaker) has integrated turn signals, but I wasn't confident they'd pass my state's inspection rules.

Instead, I ordered these flush mount LED signals from TST industries.

The signals fit through a hole I drilled in each bracket and are secured via a plastic nut.

The signals come with harnesses that allow them to plug directly into the stock signal plugs.

I switched out the stock turn signal relay with an AUDEW LED Flasher relay in order for the LED signals to blink properly.

With the signals complete, I plugged in the headlight. A third wire runs out of the headlight harness for day-time running lights, and I wired up some plugs to tap this into the low beam power wire. Because I wasn't using the turn signals on the headlight, I capped off those two wires.

Final assembly