Modern Vespa

Hi,
I've had a year of trouble free all weather riding, but last week on my 98 Pre-leader Liberty, I had the following electrical weirdness.
All the AC/DC functions are normal. ie: Ign/Choke/Starter/Lights/Horn etc. The problem is all related to the warning lights in the Speedo binnacle.
No Low oil pressure (ign warning) light.
No LH Indicator/flasher warning light.
Lights-on warning light works but, shares the circuit with the RH indicator/flasher (and pulses accordingly).
Fuel Gauge works but fluctuates and pulses with the RH indicator/flasher.
Speedo illumination not working.

I've looked through all the wiring diagrams for 4T bikes. A UK spec 98 Pre-Leader Liberty one is not available however. I've scanned the one from my Handbook and even that is not truly representative.

I've cleaned all connections at the two connector blocks where they mate with the flexible circuit "board". (More than once!)

Has anyone had a similar experience and/or know of a fix? I'm fairly up to speed with electrical diagnosis, but admit that my head hurts and was hoping someone might say, "Do this or that".

Ooh? Where's me avatar gone?

The ground connection in/into the headset has died. My first guess is that it's a corroded/dry joint on the circuit board itself, assuming that everything outside of the headset works just fine. If not that, it's a problem with the wire (probably black?) that connects the headset to ground somewhere in the loom or directly to the frame. Multimeter time...

Morning Jim, Thanks for your thoughts/confirmation. I wince already at the number of times I've disconnected that flimsy circuit board...
Hope all is well in Pleasant Hill. (Looks great on Google Earth)
Cheers ®ich

Found the problem.
The Black Earth Wire from the loom connects to Circuit Board.
But there is no conductivity from that connection even as far as the first instrument light bulb. (Less than an inch).
Does anyone know of an electrically conductive paint/adhesive so that I can bridge the flaked away copper film? It must be able to withstand the reconnection of the terminal block.

Can you solder a small wire over the bad trace, perhaps directly from the good trace to the terminal? There is a conductive paste on the market but it can't replace a missing trace.

Cheers and good luck,
Bob

Thanks for the reply, Bob.
I used the term "circuit board" loosely. The circuit "film" consists of a wafer-thin track, made of copper foil, which is sandwiched between "cling film". I don't think soldering is an option.
Somewhere back in the past, I heard of a conductive paint used for repairing rear window demist/de-icing tracks. But I need something a bit tougher than that I think. Or even a combination of adhesive copper tape and some paint.
I'll keep at it and let you know how I get on. In a perfect world, I'd do a custom rewiring job and junk the original fitment... But a quick fix is what I need at the moment. (Bike is used daily) Thanks again.

Yes, you can buy conductive paint (Maplins for one) but it won't do the job, it is only good for very low current situations. Also it'd be a bugger to make a good connection with it to the flexible 'circuit'

Find another item that is soldered onto the 'circuit', and use a trace wire between the two soldered joints to bypass the break.

Thanks again Bob/Jim for your lateral thinking. In one way it has helped. Today I bridged the Earth wire from the Loom to an Earthing Pin on the Fuel Gauge and the pulsing I was experiencing when using the RH Indicator was gone. Fuel gauge steady and no interaction between Lights On Warning Lamp and RH Indicator. LH Indicator Warning (Fed from Upper functioning Connector) now working fine.

The problem is worse than I thought though. Where the Bottom Loom Connector Block connects to the Speedo Assy Circuit Film. All four connections have oxidized and all the copper has flaked away leaving a read lead paint finish. There is no conductivity at all. See Pic.
I've ordered some 5mm Adhesive Copper Track Tape (used for slot car racing) to stick on to the pokey-up-bits. But how to join these four strips to the circuit wiring seems impossible. I thought about pushing a pin into a good bit and trying to puddle some solder down... But it all sounds a bit... Age is against me too. Duel axis astigmatism and close up work don't mix.

For the MOT I'm going to need to get: High Beam Warning, LH Indicator Warning (I could bridge the RH Indicator to do both?). My thinking now is to see if I can source some rubber housed push fit bubs and route wiring direct from the loom. The holes for the lamps are a bit to small for normal bike retail ones. But I'm happy to open out the holes to suit.

PS: The Black Wire is the feed for the Tacho/RPM thingy. The hole under the four connectors is a slot for one of the Panel Light Bulbs.

Ugh. I think you're going to have to wire up each device separately, then join to the loom with your choice of multi-pin connector - completely bypassing the flexible strips. You'd probably have to solder directly to the tally lamps - replacing them with LEDs might help here.

Whatever, the original circuitry looks beyond sensible repair.

Can someone please help me identify a passive component on my instrument panel circuitry.
It looks like a resistor, but only has two colour bands. I'm thinking, it may be a diode, but I'm not sure.
I can't even work out why it is required, so I'll post the circuit schematic, just in case someone can help.
I'm working towards junking the flexible circuit board completely and using the B8.5d type T5 wired-bulb-holders shown in the last picture.

It could be a (fusible?) link used as a bridge across other conductors. Why this rather than a plain bit of wire - who knows. Although your drawings are very good <applause> - can you take a photo of it?

Thanks for the reply Jim. Your fusible link suggestion, made me look again. I took out the nearest bulb to the component in question. Now the mystery item was out of the circuit. I checked for continuity both ways across it and measured zero resistance, both ways! So it ain't a resistor, diode or a capacitor. So a fusible link it is then. I can't see a way for it to be protecting an over-voltage to the tank sender. So if you agree, I'll consider it redundant.

Agreed.

Sorry to hijack this thread - I hope it's acceptable..

I'm in similar headset wiring predicament with my 2005 LX50 2T.

Why Vespa used those crappy flexible circuit boards (without making them available as spares - they must cost pennies) is beyond me..

A number of panel lights are out on mine - I am deciding between simply replacing the clock / speedo unit with a (hopefully good) used one from eBay or rewire using T5 wired connectors / LEDs as above.

I am leaning towards rewiring but don't want to create an unholy mess. FWIW, the two multi connectors on my LX seem to supply as follows:

Top Connector

1 to Fuel Gauge screw (sender?)
2 to High Beam +
3 to Oil +
4 to Fuel Light & Gauge screw (marked '+')
5 to Fuel Light & Gauge screw
6 to Left Dash / Right Dash / Mid Dash / Top Dash & Main Beam

Bottom Connector

1 not connected
2 to Right Turn
3 to Left Turn
4 to Left Dash / Left Turn / Right Dash / Mid Dash / Right Turn / Top Dash & MB / Hight Beam / Oil. These are all marked '-' which I presume is common earth to all except the Fuel Gauge & Light.

If I do rewire I'd like to keep the original loom connectors so I could revert to a stock head.

Does anyone know what connectors Vespa use at the end of the two headset looms? It would be good to get a couple of male versions to experiment..

Hi le bouch,
Welcome to my nightmare. I was prepared to do a full rewire and bought all the bits I needed when I saw an online auction for a 2002 ET4 complete speedo surround/switches/gauges. I knew it was a Leader engined model, but took a gamble and bought it.
I transplanted my big wheeler speedo into the ET4 housing and although there were subtle differences with manufacturing changes from my 98 Pre-Leader Liberty, to 2002 Leader ET4. The flimsy circuitry and housing was backwardly compatible.
I had a redundant immobilizer code LED which I had to tuck out of the way.
But otherwise everything fitted and functions perfectly.
I have a spare ET4 Speedo and Fuel Gauge assembly (No housing, just the instruments and their dials) with 14,000 on the clock if anyone wants one.

So le bouch, I can't help specifically with your model, but someone might chip in with some advice.
Your question about a Male connecter to fit your existing one: I doubt it.
But you could temporarily 'Tap' into the loom behind the connecting block, with Scotch Loks, or 3M T-Taps.

Glad you got yours sorted!

I will try to do the decent thing and report back with my progress. I almost bought a used clock set today but worried that I'd be just buying another load of corrosion I ordered the bits to rewire instead