I have an old style working volt gauge i want to install im my gt breadvan. I Had a look on the tube but still confused 😕

Two terminals on rear , one i assume positive and other ground ? Not worried about light in the gauge as its missing.Does the ground wire go to neg on battery terminals?

So where do i connect positive ? And will i need inline fuse on positive side ? If so what amp ?

Also what size of wire i should use 18 awg ?

And help is much appreciated.

Kind regards all and have a great Christmas.

I'd use an ignition switched live, otherwise it'll drain the battery. You shouldn't need a heavy wire, but do put a fuse in the circuit because old gauges can do unexpected things. Whereabouts are you planning on fitting it?

Edited 13 December, 2025Dec 13 by Yeti

Not sure on location yet but I won't be cutting dash up. Switch live from the ignition barrel?

If the gauge measures 120 ohms (like the Smiths voltmeter in MG) it will draw about 0.12 amps max. Too much for standby, so yes switched live.

Or fused, switched circuit like rear window, cigarette lighter.

And even 30 swg thinwall cable would be thick enough (can carry 0.5amps).

So 18 awg is overkill ? Not sure where I got that from probably u tube 🫣

So I can pull a live from cigarette lighter ?

I don't actually have a cigarette lighter.

Interior light, Cig lighter & Radio are fuse 11 on mk2.

So not sure now, sorry.

I thought key needed to be at Acc position for radio but it remembers stations when key removed. So it must have both switched and standby feeds.

And interior light does not need key.

Will cig lighter work without key?

Mk2 wiring diagram says cig lighter U1 is switched live (via the X contact relief relay J59).

1 hour ago, dvderlm said:

I don't actually have a cigarette lighter.

Interior light, Cig lighter & Radio are fuse 11 on mk2.

So not sure now, sorry.

I thought key needed to be at Acc position for radio but it remembers stations when key removed. So it must have both switched and standby feeds.

And interior light does not need key.

Will cig lighter work without key?

Not sure cigar lighter works without ignition on as I cant test as I have the hole dash out at moment. Just thought its a good time to do wiring easier access while dash is out.

Update , I used this spade connection on the fuse box and it's only live once ignition is on. Second wire was ground on same point as dash ground.

It's not ideal place as I will most likely have to modify the fuse box cover .

It's working but again looking at helpful comments please. ?

Do i still need inline fuse ?

There will be an ignition on supply on the heater blower switch that might be easier to use rather than that lead from the fusebox and yes I would still protect it with an inline fuse

42 minutes ago, nige8021 said:

There will be an ignition on supply on the heater blower switch that might be easier to use rather than that lead from the fusebox and yes I would still protect it with an inline fuse

Excellent I shall check it out tomorrow 😀

I left as is but with inline fuse now. I made my own holder bracket etc. Thanks all for help.

Edited 29 December, 2025Dec 29 by 1vw2many