Where to find switched power source?

[MeatyCrab]

Hiya,

So I'm trying to wire up an autometer a/f guage. I've had a poke around the fuse panel, but I can't figure out how to tap into a switched power source (ie one that is only active when the ignition is on)...

any clues? pictures?

cheers,
BK

 

[Alec]

Find a fuse that is ignition controlled but that you don't use very often. Maybe the power window/dome light fuse or something. Then all you need to do is remove that fuse, stick the bare end of the wire into one of the slits, then stick the fuse back in over it. Preferably you want to use the downstream terminal (the one that is not on if the fuse blows) to protect the new circuit.

Make any sense?

 

[rokke17]

Break out the DVOM and start testing circuits, you can speed it along by making intelligent guesses as to which circuits to try.
You can also buy fuse taps, which plug in to the spot where a fuse is and provides a place for the fuse to plug in and another wire, which can run to whatever.
Not sure if they make them for the small fuses in EX's though.

 

[ld50]

To find it is pretty simple. You need a test light. These are screwdriver looking things with a pointy end, a light inside, and a lead with an alligator clip off the other end. You just clamp the clip to ground and turn your ignition on while poking the sharp end on the fuse terminals. if it lights up, turn off the ignition and try again. No light now means you have found switched power. take out the fuse and you can determine where the hot side is so you can connect to it and utilize the fuse.

These are real cheap and you don`t need to know how to use an ammeter or whatnot. the sharp end is handy for poking through the insulation on a wire that you can`t get to the end of, just don`t stab yerself.

 

[MeatyCrab]

Thanks guys,

I was doing that when I was checking for one before...I used a needle with an alligator clip attatched to a lightbulb though...even cheaper than cheap...

I just couldn't find one, so maybe I'll try a few more...

Cheers,
BK

 

[MattHarrell]

You could always tap into the line for the radio. One should be constantly on and the other switched. That's what I did for my overhead console. A gauge or two shouldn't be too much additional load on that circuit

 

[Alec]

Originally posted by MattHarrell
You could always tap into the line for the radio. One should be constantly on and the other switched. That's what I did for my overhead console. A gauge or two shouldn't be too much additional load on that circuit

Except you don't want to use a circuit that's used often like the radio because of power fluctuations. Any fluctuation in the power to the gauge could disrupt it's operation. Not harmful, just not accurate.