Hello technically wise folk. I hope you are well.

Thanks to twofiftyAZU, my new speedo arrived today, and as my boss isn't at work tomorrow, I saw it as an ideal chance to make a new dashboard whilst earning overtime.

In preparation for this, I'd bought some new switches from eBay, just simple ON/OFF type toggle switches.

Having removed the dash, and the existing switches, I noticed that they aren't simple ON/OFF affairs, but have more than the two wires I was expecting to find.

This is the wiper switch:



Why does it have three wires? I thought electricity went up one, down the other and hey presto, the wipers worked. What's the extra wire for, and is there any way I can make my new toggle switch work? Is one wire something to do with making the wipers park after they're turned off? I can make do without that if so.

This is the back of the hazard warning lights switch:



Again, same question, is there any way that I can have the hazards working off of an ON/OFF switch? Or am I stuck with the standard one?

This is the back of the speedo light:



How does it work with only one wire? should there be a second one to the other connection? I've no idea if it works or not, having never had the car on the road, but again, I thought electricity had to go up one wire, through something (like a bulb) and then out the other side again, is this right?


And finally...

This is the newer speedo, and the older speedo. The fuel gauge on the newer one has three wires going into it, a yellow one, a purple one, and a black one, the older speedo has just a yellow and a purple connection. It also says '6V' on it (which I assume means six volts?) Am I going to have to do without a fuel gauge, can I use the gauge from the later speedo in the older one, or will it work fine with the black wire dangling behind the dashboard, out of sight and out of mind?




I HATE electrics.

Russ, the speedo light will probably earth through the panel and then the bodywork.

Not all switches are simply on/off - they may switch in and out different circuits at once.

That highlights the level of my electrical understanding. I assume when I want to turn something on i press 'on' and when I want it off I press 'off'.

Especially hazards -- really quite complex... When they're switched on, the whole of the normal indicator switch is "cut out" of the circuit - the hazards have to work with the ignition off, the normal indicators might or might not depending on the age of the car.

Russ - have a look at the wiring diagram on Vic's site - http://www.2cvstuff.com/2CV_yourstuff_W ... grams.html

It is impossible to concentrate and to answer with that back ground

Ok, now that my eyes have refocussed...

As you suspect, the extra wire on the wiper switch is to allow it to park (it might possibly also 'electrically brake the motor so's it stops more quickly in the right place - I'd need to check.) Bottom line, if you leave that wire out, the wipers will perform an entertaining slow down when the switch is turned off, and you'll have to learn to judge where the best 'turn off' point is...

I have a sneaking feeling that a non-parking wiper might be an MOT issue too, but that would need to be confirmed.

Are all your toggle switches 2-wire (single pole/single throw)? Does the supplier make matching 3-wire efforts (single pole/double throw)? Or even 6-wire ones - (double pole.double throw)?

Yep, the hazard light switch is a nightmare as I found out when trying (and failing) to change a Ford Cortina item to a Classic Mini type... The only way I can think of of making this work is to use a relay with the correct layout, and then have this relay turned on and off by your toggle switch. I reckon that's quite doable, but I, er, cough, have some suspicions about your 'lectrickery abilities...

The speedo light is either earthing through the metal speedo casing, or else one of the wires has broken off - yes, you are correct; leccy needs a return path.

The 6V fuel gauge just ain't going to work without modification - if you connect it as is, then it'll likely melt

Do you have an electronic multimeter? If so, set the resistance control to its lowest setting and take a reading across the fuel gauge terminals. I'm guessing the reading will be about, ooh, 100 ohms give or take (Pure guess, but I think that kind of ballpark.) Whatever it is, if you get a highish-wattage resistor of as near this resistance value as possible, and then fit it in series with the gauge (ie: you 'cut' one wire going to the gauge and 'insert' the resistor), then I reckon that should do the trick.

(If you can get me the actual resistance of the 6V gauge, then I 'should' be able to work out what resistor you need. It's not a complicated thing to work out, but I need to clear my head to make sure I'm not leading you up t'garden path Ebay has plenty of component suppliers.)

When I rewired the Bed, I remember that the hazard switch inparticular has to re-route the flasher unit so that both it and the indicator switch can operate the lights (remembering that the indicator switch operates 2 whereas the hazard switch operates 4).

The wiper switch instead of being a simple ON/OFF actually switches between one circuit or another, in this case it's switching the motor between the normal supply and the brake circuit supply (which is then cut of by a cam).

(What I ended up doing about my Cortina/Mini hazard switch problem (actually, it was for a Cortina-based Marlin kit car for which I built a new dash designed to take the Mini switches) was to keep the original Cortina hazard switch, but hide it under the lower edge of the dash out of sight!)

You might want to consider simply leaving the existing hazard switch as it is, or even reposition it somewhere else if you don't want it cluttering up the new dash. As long as the actual hazard warning light is visible, then it's ok!

Oh, ballcocks. Never even thought about that.

Yes, of course it'll be 6v. You're going to need to do some fiddling to make the fuel gauge work without the magic smoke escaping, probably a big resistor in the live feed. Where's Mike Phelan when you need him?

I like that, I think that's an easier option for me.

I can probably live without a fuel gauge Adrian, but I'll get daddy to help me do as DA suggests so maybe I can buy a resistor and mend it. I'm wondering if I can make a combination hybrid speedo using the old a new ones. The fuel gauge from the new one and the speedo from the old, in the newer casing?