7 replies to this topic

[blackbelt1990]

Hello all..

I've bought a volts gauge for my dashboard and can't seem to wire it in properly. I've had it in two circuits which both have a positive live and it's blown the fuses in both. Is the only way round this to wire it directly to the battery??

Thanks, Ryan

[Bungle]

switched live and a earth is all you need

dont know why the fuse blowing unless its faulty

[dklawson]

Voltmeters only have two connections (excluding the light). If you are blowing fuses with the volt gauge, you have something wrong with the gauge. Using jumper leads try connecting it directly to the battery... but do it this way.

Connect wires directly to the battery. Some distance away from the battery, connect a single jumper leads to one gauge terminal. Tap (not hold... tap) the second wire to the gauge's second terminal. If you get a shower of big sparks, don't use the gauge, take it back. If the gauge works, you've got some other problem. (Perhaps earlier you wired the gauge between two live circuits instead of between one switched circuit and earth).

In general it's a bad idea to wire any gauge, particularly a Smiths volts gauge, directly up to the battery. The Smiths volt gauges pass a lot of current and you'd quickly drain the battery if you didn't use a switched circuit.

[sinister]

Heres how i wired mine up:
took live feed from the fusebox which is only live at position 2 on ignition switch (didn't want gauge working when ignition at position 1 ie listening to the radio but this is purely my preference). connect this to either connector on rear of gauge.
Earth was taken from the other connector straight to body. It needed to be a dual earth to the gauge body for the light to work (older metal bodied gauge). This was linked to the bracket fixing stud.
And power for the illumination was spliced in to the illumination wire in the plug that goes into the back of the instruments (red/white on my 1995 sprite).
HTH

[dklawson]

One last question. Is this a Smiths gauge?

Smiths volt gauges work by resistance heating just like the fuel and temperature gauges. So, they are NOT polarity sensitive.

If you used a VDO or other aftermarket gauge, a lot of those ARE polarity sensitive. If you wired up an aftermarket gauge where you randomly chose which terminal to hook up to the switched power, you may have damaged the gauge.

That said, you did mention that this gauge had a metal case which implies it's probably an older Smiths unit. Examine the back of the gauge. Both of the spade-lugs should be mounted to/on insulator pads. If one is missing, you could have a short to the case ground. If both insulator are in place, check the gauge as I mentioned previously and let us know what you find.

[blackbelt1990]

it is a smiths gauge... this one in fact!

but at the moment I'm thinking of using a battery condition gauge instead.. I suppose this is wired the same way?

Thanks guys, Ryan

[dklawson]

The auction pictures certainly are nice looking.

Test the gauge like they did, by connecting it directly to the battery as I mentioned earlier. Do you have a volt/ohm meter? If you do, check that neither of the terminals has a short to the gauge case. It's not supposed to... but it might have happened. If one of the terminal is shorted to the case, just make sure to use that for your earth connection and you'll be OK.

A battery condition gauge is just another name for a voltage gauge. I'd troubleshoot this one completely before buying another.

[sinister]

Looking at the pictures of the gauge it should wire up in the same way that i did mine, being a metal bodied one