[hairpin]

Those of you that have messed with doing mods to the rear lighted area of bike, specifically the license plate light and turn signal assembly, can you verify which electrical wire goes to the license plate light?

I checked the back of my bike and it looks like the orange, green, blue, yellow wire pack near the battery goes to this area. And because green, blue, orange seem to be for turn signals, I thought the yellow one is for the license plate light. These are all 12 V and non-LED right? Only LED light at back should be the brake light and is in a different assembly.

Maybe I need to order the Grom service manual... cause I'm failing at this...

 

[pile o' zuma]

Yellow = 12v
Green = ground

 

[hairpin]

Yellow = 12v
Green = ground

Sweet, thanks!

 

[hairpin]

So I'm trying to get an alarm installed, but having trouble tapping into the switched power line (i.e. the yellow wire going back to the license light that gets power when you start ignition). The alarm doesn't register it even though the lighting at the back seems to work. So I tested the wire against the battery. I get 12.5V @ battery and 7.4V @ yellow wire. Is this normal? Something wrong with my grom? If normal, I just might not be able to find a good wire to tap into and have to return the alarm unit. Worse, is if this is not normal and I have something sucking power in the wrong spot on the bike.

Any opinions? When I test with a voltmeter, I'm checking the wire directly that I spiked into with the blue connector in pic below removed and right next to battery.

 

[G19Tony]

You should order the service manual anyway. You can never have enough data.

 

[mattallac]

I'm having the same problem , my yellow wire is only registering 7.4v also

 

[Capn Kirk]

I am going to take a stab and guess that the license plate light is powered by the generator alone and not fed off of the battery. It only lights up when the engine is turning (I found this out when installing the tidy). When it does light (at idle) it pulses in intensity with the beat of the engine.

Since installing my voltmeter, I have noticed something interesting but not surprising. When at an idle, most of the time the generator is not charging the bike at all and the bike is actually drawing from the battery. At a stop and idling, the voltage drops to ~12.0 volts. Once I rev up 1st (before even shifting to second), the RPM's come up and I am back to a proper charging voltage >13.2 volts. This charging voltage holds well as long as I am rolling. Next stop, voltage drops back to ~12.0.

 

[mattallac]

I tested with the motor running and reved it up and still 7.4v

 

[pile o' zuma]

Hmm. One of those, "well I'll be damned," moments.

So its a resisted voltage within the harness.

 

[gromathon290]

I had the same issue when installing an l.e.d. plate light. I am reading the same 7.4vdc. For switched power to run my plate light I used the wires going to the first sub fuse. Both sides of the fuse are switched with the ignition so it doesn't matter if you use the 2 blacks side or the red/black side. Switched battery voltage and an illuminated license plate are the end result