Modern Vespa

My 2007 GTS 250 has suddenly started blowing the 7.5 W fuse that goes to the instrument panel illumination and rear running light. (Nice that the two are tied together, otherwise I wouldn't know that the tail light was out! At least, I wouldn't have until that cop stopped me. ).

I replaced it once, hoping it was a flakey fuse. Blew again yesterday. I replaced it and it blew again almost immediately. I do have the Admore top-box lights on the back, that go thru that fuse, but I've had them on for over a year and no problems until now. (But I disconnected it just as a test).

Any ideas how to track it down? No obvious places where the wires have rubbed thru...

Thanks for any suggestions. Hopeing to fix this before Amerivespa...

-Dan

I'm not sure where to start,you'll need a meter to check current .good luck

A fuse blowing almost instantly after being changed is a good indication of a dead short somewhere in that circuit. The very first thing I would check are the connections where you tapped in for your Admore kit.

How to use a MULTIMETER to diagnose electrical problems.

It's likely a wire with insulation that got stripped ( probably from rubbing against areal part that is grounded) so on an occationally like going over a bump, the wire touches the metal causing a short and blowing the fuse. Sounds like it took a year or so to wear through the wire insulation. Just my guess

Best
Miguel

Thanks everyone for the suggestions. I think you're right, Miguel, it must be a connection rubbed thru somewhere and shorting to the frame. I haven't had time to give it a thorough going over yet -- I'm riding my "backup scooter" to work now until I find the problem. I did notice the last time it happened was right after a hard stop at an intersection, which lends creedence to the intermittent rubbing against the frame theory.

I'll post what I find after doing some investigation and meter work tonight.

-Dan

I think I found it. I spent a few hours yesterday inspecting and wiggling wires, but only found one place where a wire was getting pinched under the pet carrier. So I move the wire, and went for a test ride -- and blew the fuse again. I noticed it went out when I went over a speed bump, so replaced the fuse and more wiggling and jumping up and down on the scooter, to no avail. So I removed the pet carrier and went for a ride -- blew out on the speed bump again! More inspection, moved some wires. Then took my wife for a ride to the store -- and fuse blew when we went over the bump from our driveway. Aha -- something to do with the seat. I remembered the wire back to the top box goes from the vents, under the seat, to the top box. Sure enough, it was getting pinched. But no insulation break, and wiggling it didn't blow the fuse. So as a test, I put in some blocks of wood under the seat to raise it up so it wouldn't contact that wire, and now it seems to not blow the fuse anymore! I rode over lots of bumps and seems solid.

I drove to work this morning with the blocks in. If it doesn't blow the fuse by the time I get home, then I'll declare it must be the problem and then figure out how to solve it. I can cut away the plastic under the wire and see if that makes for more room, or possibly cut a notch in the seat cushion. Not happy with either solution, but I can't see any other way to route the cable up to the top box from inside the body...

Pics below to show the wire and the wood blocks I put in to test my theory that it was that wire...

At least now I know, and hopefully will be able to fix it and still take the scoot to Amerivespa.

-Dan

Great job locating the wire! The wire might be broke and separates on a bump and then blows fuse when it touches in the break inside the wire coating.It doesn't have to be bare wire contacting metal to blow fuse.

Good point. I probably should slit open the outer casing so I can see what's going on in there, and reconnect it if broken. I was hoping to avoid it, because after soldering and retaping, it's going to be thicker and thus will get pinched even more...

-Dan

I'd rewire and reroute wire .Take the trunk off and drill a hole by the bracket.Use a rubber hole grommet so the wire doesn't rub the metal.Itd be a pain but will solve problem in the future.

Is this where you think it's hitting ?

It's not getting smashed here,there's too much room in slots.It'd have to be between black and maroon paint if its the seat hitting.

Yes, there's a groove in the seat where it's mashing the wire. I think it's pressing the wire down against the grey plastic (the bottom of the slot). So one fix would be to cut off the plastic at the bottom of that slot, so it's laying against the metal body. Would give it about 1/4 inch more room. Or I could reroute it and drill a hold thru the body I guess. I hate doing that, but I suppose it would be the best option.

-Dan

If your looking easy route.Pull a few staples out of seat cover and notch the seat and restaple the cover.Or spend a lot of time and route it and not see it in the thing that hold the trunk,by drilling right here....in photo.

I think I've got it fixed. I took the easier way out, and decided to cut a notch in the seat to stop the pinching/crushing of the cable. I marked where it was pinching with a piece of tape, then removed the seat, unstapled the covering around the spot, cut a v-shaped notch in it, and restapled the covering. I put on a couple pieces of black cloth tape to make it look neat.

So I thought that was it, but when I went on a test ride over some bumps, the fuse blew again! So then I tried pulling the wire out about an inch so that the crushed section was no longer under the seat. NOW finally it seems to be working solidly. Even went for an extended ride with my wife riding pillion and the fuse did not blow. So I feel confident enough to take it to Amerivespa. (But not so confident that I didn't go to the autoparts store and buy 5 more spare 7.5A fuses...).

If it fails again, I will cut open the wire casing and take a look, and resolder and tape any broken wires. But I figure if it works like this, I'm better off not cutting into it since once I do I loose the watertight capability, and soldering and taping it will just make it fatter and more prone to pinching.

Thanks everyone for your suggestions and advice!

-Dan

Well it started blowing that fuse again whenever my wife rides with me. I had a harrowing ride home at night thru the Santa Cruz mountains without a tail light. So I took a look at it this weekend. I slit open the insulation on the cable where the seat contacts it and it was fine -- none of the wires inside we're shorting. Next I traced the wire back to where I spliced it in, and I found the problem. I had run it around and under the gas tank, using the stick on clips supplied by Admore. Well the clips detached and the wire was hanging down loose. The added weight of my passenger compressed the suspension enough that the wire made contact with the hot muffler. It melted thru the insulation and the wires would short against the muffler and blow the fuse!! No passenger and the wire stayed above the fuse so it didn't short.

The fix was to reroute the wire to go in the space between the gas tank and the right body cowl. I used a stiff wire to fish it through. The cable wasn't long enough so I undid it at the positaps where I spliced it in, ran a new cable and spliced it into the old cable right next to the PC board controller on the original cable. Now it works great and I'm confident this is the final fix. Whew!!

-Dan