Volt Meter Drama

[lowndsie]

I hooked up a speco volt meter to the existing clock wiring. The clock is totally removed. The problem i'm having is that it tells me the battery current when the car is off (which is great for camping reasons) but when i turn the ignition on it cuts off. The needle goes straight down to zero. Is there anyway i can have the guage working whilst the ignition is on as well???? would be good to keep an eye on the alternator. But i still want to be able to see how the battery is while ignition is off.

[TRITON90]

Sounds like youve got the earth wire hooked up wrong. Re check your wiring, make sure you have the earth wire right, or run directly to a good earth point behind dash.

[Utemad]

I agree with the earth idea. If you had the voltmeter hooked up to 'battery' on one side and 'accessories' on the other then it would work only when the ignition was switched off as you describe.

This is how some flashing LEDs (fake alarms) are wired up.

[roberts]

i have just brought the same gauge and have know idea how to hook it up

or what sort of wiring to use

[lowndsie]

there's no earth wire. could i just run a wire from the unit to a earth point?? i think thats how it works.

[TRITON90]

yes, just find a good clean metal part of the dash and screw the negative wire to that. If you havnt got a test light i suggest buying even a cheap one, as they are invaluable when chasing electrical faults or connecting new equipment.

[lowndsie]

forgive my lack of knowledge but i'm all confused. theres a positive and neg wire already that was used on the clock. i just used the same ones to power the voltmeter. and i used the same wires for the light on the gauge. if i had no problems with the clock.....why do i have them with the meter???

the earth wire is just an extra wire? one that runs from the unit to a point? do i leave all the other wires attached?

[TRITON90]

Usually there are four wires to the clock, battery power, ignition power, dash light power and earth. Make sure you have the negative wire connected to the earth wire.

[Scrapper]

You would be best, as suggested, to run your own earth wire if you have trouble finding if the clock earth actually is an earth (a multimeter set to resistance (ohms) mode can check this - should be zero (or near enough).) Anything more than about 0.3 of an ohm is not earth. Anything that has volts on it isn't earthed either!

Be aware that the volt meter doesn't run for free - it is drawing power from your battery. Cheaper meters like Speco (I use them too, so I'm not knocking them) often draw more power than better instruments like VDO for example. This means you could end up with a soggy battery if you don't drive the truck for a few days.

My recommendation is to tap from the fused side of a wire in the fuse box (so the meter circuit is protected) of a constant wire (one that has power to it all the time) and put a rocker switch in line with the meter. That way you can check the status at the flick of a switch, without the key, yet avoid draining the battery when parked for longer durations. Obviously you can leave the switch on when the engine is running...

Ask if you require clarification.