volt gauge off a head unit


Torque Junkie
nissan 200sx s14a
hi guys and gals,

recently purchased a savage volt gauge/meter from a local shop. i know the reccomendations are to wire it off my ignition line but one off my mates has advised/told me i can wire it off my head unit,

1. is this possible
2. will it give the right readings
3. has anyone done it this way and can they tell me how they did it or give me a step by step plz.

cheers josh await your replies
I wouldn't wire in with the headunit myself.
You risk getting interference and when you get some bass it will prob give you wrong voltage readings.
It's easy enough to do it off the ignition.
Agreed unless you have monster wiring between battery and HU. A volt meter is very unlikely to introduce audio distortion these are very high resistance devices. If they use J-FET input devices then the input impedance will be of the order of 20 mega-ohms or higher.
cheers for the info,, um do any of you know how to wire it up , an can u tell me or show me how to plz?
cheers josh
It will probably have 3 wires.

-ve or earth is common, just choose any suitable ground point.

The other pair of wires - 1 will be to an ignition switched live - this is for the voltage reading. The other will be to something switched with the sidelights.
well i thought stuff it , mainly wanted it for looks so temporarily wired it off me head unit and at a later date gunna wire it off ignition instead, also i plan to get an oil pressure gauuge and possibly a few other gauges, cant wait lol. i get interferance when i stick my indicators on and thats it , i wont get distortion interferance cos i dnt have any subs cos im goin rally look car, so back of car is stripped out, lol , but all is good, will probly be wiring it off ignition in the next few months so it will work properly ,

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