good power sources

what is a good power source?
i have tapped in for power so many times it is crazy.

Ignition harness. Remove the upper and lower steering column covers, and voila! You got constant and switched 12v. Once a friend of mine had a whole bunch of things that needed power, so we made 3 wire extensions to a fuse block we added on (bought from the auto store): we had one main wire tapped to the white for constant 12, one to the black-with-white (i think) for switched 12, and one to the steel body for ground. It was sweet cuz once you add an extended fuse block, you could add any damn thing you wanted.

can you run a new power wire off your battery? if i did run a new one off my battery for stuff like gauges, lights, and disc changer do i need a fuse.

to a fuse block we added – you made a fuse block…can you explain more? i want this done right

you should always run a fuse… your car could catch on fire.:frowning:

what kind of fuse? i would assume something different than the stero kind.

fuses are fuses… you need a fuse that is equal to what you are trying to power; i.e. 20, 30, 40 amp fuses. they are called different things like in-line fuse holders. but they also make smaller ones for smaller guage wire, you can get one at radio shack.

I always prefer to run any real power sinks off of a relay that is switched from the ignition and powered from a fused line from the battery. You can run almost anything this way and it doesn’t risk shorts in the stock harness. Look around and you will see alot of people complianing about shorts. Too much stuff on the factory harness can cause overheating and failure. If you screw up and cause a short in the ignition system, then car no start no more.

Relays rule; use them, learn them, love them.

how do you run a power sinks off of a relay that is switched from the ignition ?

It’s pretty easy. Attach a wire to the battery. Then put an inline fuse in, attach that wire to the switched relay contact. Run a ground (can be a small wire 20-26 ga. works well) to one side of the relay coil. Run another small wire to a switched ignition source. Since the relay draws practically no power itself this can be put on any switched circuit. Then Run a wire from the other switched contact to what ever your trying to power.

Most automotive relays are rated at 30A so you can run almost anything off of them. This keeps the factory harness safe, and the relays only cost a couple bucks. I’ve got a few in my car now. If you need the pin out on the relay I can get it for you if you dont understand the diagram on the relay itself.

If you want a diagram I can draw a quick and simple one up in paint and e-mail it to you.

any quick and dirty sketch would help. thanks for the replying and helping

Re: good power sources

Originally posted by tegdablunt
what is a good power source?
i have tapped in for power so many times it is crazy.

You would be amazed how many power sources are available at the fusebox on the driver’s side kickpanel… Also, I believe there’s an accessory harness burried behind the dash between the defog. button and the center console. If all else fails, run power from the battery itself with a fuse inline within 6-12" and then use the closest chasis grounding point.

What exactly are you trying to power?? I ran an 1/8" adapter plug from a fused 20A circuit off the fuse panel to run a radar detector on my sunvisor for years… I have run 3 amplifiers, an alarm system with strobes, a backup battery siren, piezo siren in trunk and a dual Delta88 horn under the dash from a power wire run from the battery to a fused ground distribution block. The nice thing about running to a dedicated fused ground distribution block (especially for an alarm install) is that one shorted circuit will only blow THAT particular fuse. Case in point… You have 4 sirens attached to your alarm system and a potential theif wants to knock out the noise… They could short the siren’s power wire from the alarm brain and likely succeed. Now… if they tried the same thing with 4 sirens that all had individual fused grounded connections, each circuit would need to be shorted individually to get the same result. If you are going to run a mountain of accessories, I sugest either removing and rewiring circuits on your interior fuse panel or running power from the battery to a dedicated fused distribution block (you could put this in the glovebox, ashtray, etc.).


aka neex.

btw… if you need to switch a high current demand circuit, use a relay to power the circuit on and off with a lower voltage pulse to the relay’s coil. This is also beneficial because you can use very small switches to power very powerfull circuits. An example would be hooking up a reed switch or micro switch to engage the horn. A horn draws about 35-40A usually and so it should use a relay to switch this type of circuit. If you are wiring a LED for a dash light or something, it may not be as critical. DO NOT FORGET TO FUSE YOUR CIRCUITS! Add up the total draw of the circuit you are installing and be sure that the fuse is as close to this or maybe 10% higher max.


Things I am going to power from this wire. Sony 10 disc changer, extra led to flash with my alarm led, my glow gauges, my temperature gauge, and now that you say it an extra siren.
How hard is it to wire in an extra siren?

Anyway I want to run power from the battery to a dedicated fused distribution block. But what gauge wire should it be and does each wire I run off that need a fuse of can I have one fuse for the dedicated line?

If its a fused distribution block then you don’t need any in-line fuses because they plug into the distribution block. I prefer 10 or 12 ga wire to power the block. 12ga is easier to work with and should be ample for you needs and some minor future additions. I would probably only use 14 or 16 ga to run some of the accesories after the fuse block.

The extra LED can be wired parallel with the stock LED. LEDs use VERY little current. The changer would probably be good on 14 ga. I don’t know what current your glow gauges draw so thats hard to say. The temp gague can easily be run off 16ga. The extra siren probably car run off either 14 or 16 ga.

Again I would put a relay or relays if necessary between the battery and the dist block . Otherwise this block will have power all the time and not just when the ignition is on.