Electronics Basics and Reference

I would like to wire up LED bed lights using a door switch that I will install so that the lights come on whenever the tailgate is down. I had a 2007 FJ and there was a 12v always hot wire at the back. I don't think my 2014 tacoma doc has that wire . I do know that the factory tow pkg 7 pin connector has a 12v 30a pin ( I believe that's for charging trailer brake battery) I would like to tap into the tow harness and use that for powering the LEDs . the problem is I need to make that pin always hot. I'm thinking I could jump out the relay so that it's always 12v . I could use some help with -- how to jump out the relay. also after reading the excellent tutorial on wiring I want to check and see if this is a good method of wiring.
so .
I make the tow pin 12v always hot by jumping out relay under hood
I tap into that wire at rear of truck and put an inline 5 amp fuse and run to the 12v+ of the led light strip
I install door switch to be activated by tailgate and wire to 12v-of led light strip
will this work ok?
I would appreciate any info / pics on how to jump out relay

 

excellent explanation

 

Soooo glad I'm only a plumber ........ This is mind boggling .

 

I read your PM too, here's some thoughts...

I like your thoughts, but in my personal opinion, it is easier to run a new wire along the frame than it is to "hack" the OEM wiring harness and/or relay/fuse box. You run into potential warranty issues too if that matters to you.

Finding a suitable connector to install into the relay slot is probably feasible, but that'd require a bunch of research. The only other way would be some sort of wire connecting the 2 points. However, this would be a hack wiring job and looks unprofessional; you run the risk of the wiring coming loose and shorting to something it shouldn't. It'd have to be a beefy wire to handle 30A too (don't risk using something smaller in case you actually plug a trailer into it, or the guy that ends up with your truck when you get rid of it).

Another option is to leave the relay installed, but wire it such that it is on all the time instead of w/ the ignition. However, this requires you to permanetly cut wires...basically you'd cut the wire coming from the ignition switch that normally activates the relay and connect it to the battery instead (with a suitable fuse too). But again, this is intrusive and modifies your OEM harness. Good luck finding the specific wire in the harness going to the box anyway.

The first thing I would do is 100% verify that the trailer connector in fact is off when the ignition is off. Note: if it does work all the time, I recommend buying a cheap trailer wire/connector and tap off of that rather than modifying the OEM wires. Also, this allows you to easily remove the bed lights if you ever sell the truck. You can probably make a makeshift Y connector so your bed lights can remain connected and operate a trailer at the same time. Regardless of the approach, I agree that a small fuse should be used on the backend for the LED lights.

With all that said, I still suggest simply running a new wire. There's a bunch of posts regarding how to run a wire along the frame (I have an example in my build thread when I added 12V supply to the bed). It is really quite simple and I think is the easiest solution for you, rather than modifying the OEM harness and hacking the relay box.

With this approach, I would fuse the wire at the battery and run the wire to the switch in the bed. With this low of a current draw, don't bother with a relay, just get a switch that can handle the current (most small switches can still handle at least 5A or more). Then wire your LEDs to the switch.

Probably not the answer you wanted to hear, but I think you'd have more trouble on your hands that it's worth.

 

ive been having trouble with my 2005 Toyota Tacoma it has lost power and doesn't run as strong as before
P0037, P0051, P0138, P0328, and P0606
these codes showed up and was wondering what might be the cause of this trouble?

 

So if I use a fuse tap to give power to interior leds I just put the tap with like a 10a fuse into an open fuse slot, run the wire to the positive side of the switch, but what about the negative? Where does that wire come from?

 

A fuse maybe? I actually just had my check engine light come on 2 days ago with a P0057 and P0102 and when I floored the gas peddle the engine would rev up but no power behind it. Turns out the EFI2 fuse was in the wrong spot. I was checking fuses the night prior to this and put the EFI2 fuse back in the wrong spot

 

This thread might not be the best place to look. There should be a number of threads on the site regarding trouble codes (I'm not sure what they are off hand, but not likely electrical-related).

 

FYI, there aren't likely any open fuse slots, normally when you need to add a fuse it is an in-line wire type or an added block of fuse slots that you add. "Open" fuse locations in the OEM fuse box are typically wired to something in the truck already.

Negative typically goes to a chassis ground. You can typically find one near the fuse box in the cab. If you're wiring in the engine bay, just use any bolt that mounts a bracket to the frame. It's a good idea to clear off any paint to ensure a solid electrical connection.

 

Ok. I didn't now if there was a negative wire that needed to be tapped into as well. For the fuse tap, would anyone recommend doing that? Like in the OP, I don't want to overload the wire. This is all still new to me so I'm trying to figure out a way that would be easier on me.

 

Although you could tap into an existing groundwire, it's not the best. Just run a new wire to any sufficient ground location in the cab or under the hood depending on where you run your wires. For example, just about any bolt connected to the body/chassis is ground. Inside the cab, typically most metal brackets are connected to ground. You'll typically find them behind the dash (i.e. when connecting a new radio) or behind the kick panels (i.e. near the fuse box). More than likely the device (i.e. lights) you are installing have pre-installed wires you can easily use for power and ground. The trick then is to tap the power wire onto a source. This where the overloading conerns come into play if you're considering tapping off of an existing factory wire.

FYI - I am the OP; hang in there... Tip: check out some of my other links and build link, you'll see ideas for wire runs. For example, when I installed power in the bed, I ran a new power wire all the way from the battery via a new fuse panel I installed (and thus avoided touching any factory wiring) and then connected ground near the bed. This reduces the material costs and hassles of running another wire back to the battery, and is safer because you don't have another current-carrying wire running the length of the truck, and is simply easier. Long story short, the chassis of the truck acts like 1 big wire back to the battery and thus is a better option to connect to it near the load (i.e. lights, etc).

 

Great info on wiring! Thanks! Sub'd for later reference if needed.

 

Can anyone tell me if disconnecting/reconnecting your battery, (as in replacing a battery), can cause problems with either the alarm system or any other electrical systems in my Tacoma? I ask because I replaced the battery in my Highlander about 6 months ago, and the check engine light was on for about a week, (and at a cost of about $50 to have a mechanic tell me I needed an O2 sensor, which I did not), before it went out on its own. Would it be a good idea to put a trickle charge on the battery wires until the new one was installed?

 

sub'd

 

No it shouldn't cause any issues changing your battery.

 

Great reference.

 

Thank you

 

subd

 

Hello,

Does anyone ever did the headlights on with dome lights when we unlock the doors?

I just read that it could be possible and I might find it useful