Modern Vespa

I did a DC conversion on one of my US market PX150 scoots a few years ago. The wiring was quite a pain because there was so little documentation for wiring in a TrailTech DC regulator...in fact I couldn't find any info online about it. Sure, lots and lots of people have performed the DC conversion on the Stella (LML), but the PX has a much different wiring harness. Long story short, it took quite a while (and some dumb luck) to figure out what wires go where.

Since I have a 2nd 2005 PX150, I figure that performing the DC conversion would be much easier the second time around (and it was).

I decided to document it this time so others can possibly benefit from this thread.

Here are links to the DC flasher and the DC regulator-

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2322090.m570.l1313.TR0.TRC0.H0.TRS0&_nkw=2+Pin+Motorcycle+Speed+Adjustable+LED+Turn+Signal+Indicator+Flasher+Relay+12v&_sacat=0

https://www.trailtech.net/accessories/electrical-accessories/7004-rr150



First off, this is was it looks like behind the battery...

I didn't do much documenting of the "floating the ground" because it has been so well covered in the past in other threads, but I'll go over it briefly anyhow...

I cut the bare solid copper wire that is soldered to the stator plate (it was soldered to the tab that the black arrow is pointing to), and relocated it next to a coil (what my pen is pointing to), then soldered a dark blue wire (you can't see the dark blue because I have a heavy wall heatshrink over the top of it) to that bare copper wire. That dark blue wire will need to be attached to one of the yellow wires on the Trailtech regulator that's located behind the battery. So do what ever you need to do to run that wire in safe locations all the way to the regulator.

Then we take a look at the stock regulator...

And the back side of the regulator...

And a look at the stock AC turn signal relay flasher. It just so happens that my non-battery T5 and my non-battery PK125xl use the same flasher as the US market E-start scooters.

The DC conversion requires using a DC turn signal flasher. And since I'll probably be switching to LED turn signals, I needed to use a LED style flasher unit. I bought this one on eBay a few years ago. It has an adjuster on the bottom that is used for controlling the rate of the flash.

The stock green colored AC flasher uses 3 wires. The aftermarket orange LED DC flasher uses 2 wires. The connector that has the two green wires plug into the terminal that has a "B" stamped into the plastic. The red AND the red/white wires will both need to be attached together, then plugged into the "L" terminal.

Wires plugged in...

A pic of the red AND red/white wire that got soldered together.

Here's a pic of the DC Trailtech regulator with the PX wires plugged into it. I had to crimp on the connectors to the TT. Also, the red/yellow wire isn't used for the DC conversion, so I capped it off with heatshrink.

The TT has two yellow wires. It does not matter which yellow wire that the "floated ground" wire (that dark blue wire that has black heatshink on it) plugs into. The blue wire (that has the grey plastic connector) will plug into the other yellow wire....again, it does not matter which of those two wires get plugged into the two yellow wires.

The white wire that was connected to the stock regulator, as well as the green and yellow/black wire (that was plugged into the stock regulator as well), will both need to be attached together...whether you want to solder them or if you make a "jumper" wire like I did.

Now to remove the horn casting, so that we can gain access to the starter interlock.

Unplug and remove the starter interlock assembly. There's four wires that will be unplugged once it's removed. Plug the black wire into the pink/black wire. Cap off the other two wires, because they won't be used.

Now back to where the battery is...

I can't remember why, but with my last PX150 DC conversion, I relocated the negative battery cable and grounded it directly to the frame. I then made up a second ground cable, and one end gets grounded to the frame, and the other end attached to the negative side of the battery.

Note that I didn't cut the original negative battery cable. All I did was bolt it to the upper threaded hole in the frame (where the original regulator was mounted to the frame).

Another view...

I wired in a 21 watt LED headlight so far, but I still want to wire in some Symtec grip heaters. I might wire up a LED spot light as well. Since I started on this today, I still need to do other little things as well (led tail light, 12vdc power to the glovebox, maybe LED dash lights?, LED turn signals?).

Very nice writeup!

That bike is too clean for 13 years old.

Thanks jim!

I bough the PX last summer. It only had about 2500 miles on it...along with lots of cobwebs under both cowls. It also had zero dents or dings. Originally, i planned to strip down the bike (in order to use the parts for other projects) and sell the rest of it off, but it was just too dang nice looking to do that. I rode it twice before promptly swapping in a PX200 engine. Now it goes a bit faster than 47mph.

I have zero electrical knowledge but enjoyed reading this. Very thorough, thanks for posting.

You're welcome! I made sure to get lots of pics of which colored wires go where. I wanted to get lots of photos of exactly what I did so that others would have an easier time following along.

Thanks for the awesome write-up. I'm going to tackle this on my '05 PX150 in the next couple of weeks. What headlight did you use?

Great write-up!

What do the yellow/black and the white wire go to? as I found on my Stella that the two spare wires were for the headlight, since it runs off the AC side in stock form.

The issue I found was the voltage drop from the battery to the headlight, since power has to travel to the headset and back to the cowl and then back to the headset. Anyway, what I am getting at is, if those two wires interconnect to the headlight I would look into using a relay for power to the headlight.

I don't remember what the yellow/black and white wires power...i think everything going to the headset? The 05 PX150 already uses a relay for the high beam (probably because is uses a 55/60 watt H4 bulb).

I used a LED Baja Designs S2 that has a "wide cornering" beam pattern for my main headlight. It projects a low and wide beam pattern. I have a few extra ones in my shop so i decided to put one of them to use.

https://www.bajadesigns.com/products/s2-pro-led-wide-cornering-flush-mount.asp

mispost

Since I planned on using a LED headlight, I had no use for the PX H4 bulb connector.

There are three wires going to the PX headlight; black (ground), brown (low beam), and purple (high beam).

First I attached the ground on the LED to the black PX wire. Then the purple PX wire goes to the positive side of the LED. The brown low beam wire gets capped off and won't be used.

The way that I wired up the headlight, I can turn it completely off while the scooter is still running. The high beam indicator (that's in the speedo) will turn on when the headlight is on, and will turn off when the headlight is turned off.

The original PX headlight...

The new LED headlight...

And what the front of the LED looks like. I got some 1/4" red acrylic plastic, and used a fancy circle cutting jig in my router. I cut two circles because I needed to stack them both together so that it would be a total of a 1/2" thick. I then cut a rectangular hole for the LED housing. Before I installed the LED, I sanded off all of the black anodizing and then polished the aluminum face.