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Best, clean +12V switched power source to tap from in the SC300 engine bay?
I've been doing a custom harness and soldering project for my LXCC controller lately and I need a bit of help. Tapping off the battery connection is easy but please forgive my ignorance on this one: where is the best, clean and safe place to tap a switched +12V power connection from an SC300 engine bay?
I'm planning to run eight 0-5V electrical gauge sensors from whatever single tap source I use and I'll be making a custom connector for all eight positive 22-24 gauge wires to feed into it with disconnects for each so that I can repurpose the gauge connections in the future if I need to.
I like to do a lot of research beforehand and stick with the cleanest and safest possible way to do this. I realize that adding electronic gauge senders is far from a new thing. I just haven't done it before.
Is the alternator the best place or is there a better location to do this from?
Thanks, all!
Last edited by KahnBB6; 02-12-16 at 07:25 PM.
Reason: Grammatical correction/cleaning
Probably not the answer you are looking for, but I ended up running a dedicated 12v constant hot wire directly from the underhood fuse box with a SPDT relay using the cigarette lighter as a turn on and thus turning it into a 12v "switched."
Did a similar thing in the trunk area for the fuel pump power supply but used the antenna 12v turn on for the SPDT relay there.
that many power source you need , you might as well have a distribution box which you tap from the positive terminal of your battery. As Intimazy said , enable the power from the distribution box through a relay that is activated when the ignition switched is on. SPDT is Single Pole Double Throw .
A distribution box sounds much better. I could even route a main negative ground into that as well to keep things streamlined. It's beginning to sound like I should do a miniature engine bay sub harness just for the gauge senders. Do people normally do something like that?
With the cigarette/accessory connection in the fuse box under the hood can I get away with a simple wire tap clamp since space and wire length is tight or would a hard solder still be recommended?
It must not be a coincidence that I had to order new battery terminals to replace the old ones
A distribution box sounds much better. I could even route a main negative ground into that as well to keep things streamlined. It's beginning to sound like I should do a miniature engine bay sub harness just for the gauge senders. Do people normally do something like that?
It is a lot better knowing where your central power supply is rather than tapping everywhere just to get power source. After a couple of months or years you know exactly where power came from and you don't scratch your head when you need to do some work again and trying to trace where power had been tapped.
Originally Posted by KahnBB6
With the cigarette/accessory connection in the fuse box under the hood can I get away with a simple wire tap clamp since space and wire length is tight or would a hard solder still be recommended?
Make sure when you tap ... wires are secured properly . If soldering is needed then do so just to make sure harsh vibration wont cause loose connections and start giving you gremlins... stuff working one day and the other day are not.
Another suggestion would be to just pull a switched power fuse (rather it be the EFI, radio, etc.) and then stick a wire into the fuse location and then plug the fuse back in. The fuse will be tight going back in, and that wire will always have a solid connection. Then there is no splicing or soldering into vehicle wiring. You should determine which end of that fuse is protected by the fuse so that you know you are tapping into the right end. You want to tap into the secondary side of the fuse, not the primary side. So, with fuse removed, turn key to ON and then check the voltage on both sides of the fuse box. You want to connect your wire into the end that has 0 volts, not 12 volts. That way, your wire will be protected by that fuse. You can use that wire to energize your relay, then use the relay to supply your power distribution. Don't forget to use an inline fuse on your main power distribution line so that your power "block" is protected from shorting and burning/fire. For your power "block", I would suggest these splicing cage clamps. I love these things:
They only come in up to 5 terminals, but they are great. Nice and compact
The part # for these is MFR: Wago. Part number: 222-415
02-12-16, 07:12 PM
Best, clean +12V switched power source to tap from in the SC300 engine bay?
