Electrical Problem


I was riding my PX’98 home from work tonight when all the lights starting flashing on and off, plus the fuel guage went up and down and the speedo lights flashed too. They then gave up completely, which left me stranded in the dark. On closer inspection, with the engine running and the lights still switched on the bulb filaments were glowing orange and the fuel guage was showing 1/4 full, when the tanks full to the brim. Not enough volts? I know little about vespa electrics - can someone help me out here or give me some clues?

Cheers. Ed.[?[]

One point to note I have a PX 99 and even with the battery totally flat my lights work perfectly, just the starter does not work.

Hey nelboy what uni u at? Im at Portsmouth.

Vespa… its not just a scooter, its a way of life!


Cheers guys, managed to fix the headlights - there was no need to panic - it was just one of those accessory cables in the glovebox shorting out to an earth strap braid off one of the indicators. As usual it was the last thing I checked! Now the b**dy indicator flasher relay thing has died! Front lights flash back ones stay on and dont flash. Switched the flasher box connects around and the reverse happened. Another thing to stick on my order list.

By the way - Stubbsy - I am living in South Belfast - I’m from Gloucester, England, but been working in Belfast for 4 years for QUB. And I agree T5 mk1s are the dogs balls.

Cheers Ed.

hi mate,electrician on the job,let’s see wot we can help you with!
as mtl said it definately sounds like a bad earth prob,cos you have lost all power.however,you could also have a problem with the regulator but that’s quite rare,but not impossible.remember as i told the lad with the 50 special vespa lighting electrics are ac (alternating current) and your starter circuit is dc(direct current).the two don’t mix.
is your starter circuit working ok? or has the battery gone flat?
if the batt has gone flat then i think you should be looking at your main frame earthing or regulator,because it has obviously affected your charging circuit.if the engine is turning ok,without any noticable loss in power,then i think you may have an earthing problem on the main wiring loom.is your horn working ok? the reason i ask is because on some pure ac models with the „duck“ type horns all current goes through the horn first.i havn’t studied the newer wiring diagrams enough to work out if they have a similar design! sorry!
remember on an ac system if you have a cable chaffed down to earth there are no fuses to b***,so all that happens is the power takes the easiest route back to the stator,ie down to earth through the frame thus bypassing the lighting and power circuit.
another thing to remember with vespa electrics is the engines’ power is generated seperately to the lighting and power,so just because the bike runs ok it dosn’t mean your lighting coils arn’t knackered!
so you could also have a fault on your stator,probably a dry joint if you have a lack of power.
electrics can get a bit complex,so if you try all of this to no avail post another note with your email and we can get in touch and have a bit crack over the fone!hope this helps

hi all just goin to work at this ridiculous hour on a at morn,but totally off the subject, here ehitchings you mention the psni.were abouts you from in the green and pleasant land?im from bangor[:dance1:]


Thanks for all your help. After pushing it home a couple of miles and being stopped by the PSNI who thought I was a scooter thief I got stuck into the electrics in the back yard with a torch. The scooter is a 98 PX with electric start, rectifier/regulator, battery. The starter motor and horn are working fine, but the light bulb filaments just glow very faintly. On pressing the starter button the lights lit for a second then went out as the engine carried on running. The battery electrolyte level was way, way down near the bottom of the cells, could just be my neglect! There goes my weekend, I’m off to B&Q for a multi-meter. Hope this doesn’t turn into one of those jobs where I replace 3 different bits before I get the right one. One more thing, when the lights started flashing on and off I could have sworn that the indicators flashed on and off when I didn’t have them switched on - could be a fault in the handlebar switches? The vespa lights went out on Halloween – spooky!!!

Cheers. Ed.[:shock1:] [:drink:]

got ya!
replace the battery,all will be fine!
what has happened is the battery has got that low it is drawing all the current from the bike.it is at such a low resistance it is almost a short circuit,thus all your lights go dim.when you start the bike the lights are ok because the starter is drawing current from the battery and the battery is not drawing charge!this explains it!queer stuff electric you know!i’m studying for a degree and i’m still no where near understanding it properly!
replace the batt.any more probs contact me!
mtl.as i said earlier,the vespa lighting circuit is ac,the starter is dc,obviously the battery only runs the starter,which is a later add on and takes the most current.after studying the later wiring diagrams i realised the starter circuit was the only 12v dc circuit on the bike,everything else is as was,ie 12 ac.
anymore electrical probs just try me,i have the wiring diagrams now!!!

woops posted too soon!
hope all this droning on is helping you to understand how the electrics work!
electrical tutorial over for now!

hey,you gotta do it if you want to get on!just hope i manage to stick it out!

Sounds like you could have a bad earth as all your electrical systems seem to be suffering. Check the battery connection and work your way from there. Also check all the wiring you can see for chaffing, especially around the engine area and in the headset. You should particullarly focus on areas where the wires can rub. I am no expert on the electrics myself, but I have found that working through the problem methodically usually works for me.

i’m not studying at uni.i’m on a day release from work.i’m a maintenance spark for the post office.gotta finish my HND at darlington college then gotta decide how i’m gonna finish my degree.bout another 2-3 years til i complete it! it’s not quite as easy when you’re approaching 30!
i made the mistake of settling for sparks wages when i finished my apprenticeship,which,if you put the hours in,is very good money!i just fancy blasting my brain a bit more but this really is the last time!!!
wot you studying then?

as i said michael,wot happened there is the power took the easiest route back to earth.bulbs are just glorified resistors. why would the power want to go through a resistor when it’s much easier to go straight down to earth!
suppose you could compare it to a walk home from the pub!!! why take the route with the hill and fences when there’s a much easier direct route going by a nice flat road which will take less effort![:drink:]

The exact same happened to me a few months ago, I shit myself well sort of, anyhoow i opened my toolbox to get my toolkit out and low and behold everything went back to normal, my toolkit had trapped the two wires in the toolbox against the frame and given a sort of short or bad earth so i taped them back up and had no probs since.Hope this helps,you never know.

Im doing BSC Psychology. i am also quite old 36 now, I also fancied a new challenge, and a change of direction from IT.

I could never afford to go to Uni when I was younger, so now im taking my chance.