Wiring an aux backup light

I have an extra fog/spot light kicking around and obviously time on my hands...
What's the preferred way to wire one up to the reverse switch?
@crashnburn80
Thanks!

 

I sourced 12V from my trailer connector, used the factory backup light as the trigger wire for a relay.

 

If you use the Search function, I think you'll find that this subject has been more than beat to death.

 

Hard to find a subject that hasn't been

 

Yup! That's the way I've always done it. And I really like Posi-taps as they seem to secure and preserve the wiring better than other methods

$15 Posi-Tap Mini-size Connectors for 20-22 Gauge Wire, Pack of 20

https://www.amazon.com/Posi-Tap-Mini-size-Connectors-20-22-Gauge/dp/B019BLZWQ0#

 

Dumb it down for me fellas, electric is admittedly a serious weak subject for me.
Is this diagram correct?
Question: So I run the trailer hot to the hot wire on the auxiliary light?
Then ground the auxiliary pod to the frame or something similar (or should it be grounded to the trailer harness)
How where does the relay wire up?

 

Here's how I would do it:

Grab a 12v relay and your favorite 12v wire. I like 16 gauge for an LED application, but go heavier for incandescent.You can color code it to make it easier to troubleshoot but, for functionality, it doesn't matter. Grab, some ring terminals and a few female spade connectors for 16g wire. Grab a fuse holder. I like the waterproof ones. Also, using the electrical sheathing of your choice is a nice touch to further insulate and isolate the wires.

1st steps:
-mount your lights
-find a place to mount your relay somewhere safe (I like behind the driver side taillight housing; it's protected and you'll be there anyway. Remove the driver side taillight). Don't mount the relay just yet.

2nd steps:
-connect fuse holder to a long length of your wire. I like to solder and heatshrink, but choose what you like. Connect a ring terminal to the other side of the fuse holder side, preparing to attach it to the battery. Remove the fuse so the wire isn't live and since you've removed the fuse, feel free to mount the ring terminal end to the battery.
-Sheath the other end of the fused wire, if you choose, and run it from the battery all the way to the back of your truck to the taillight housing. Trim it if you like, but if you do, leave it long to give yourself some room to work. Be careful with how you route the wire and prepare to zip tie it, but don't do that yet.
-Next, attach another ring terminal to a length of wire and attach the ring terminal to a bolt on part if the frame. Run that wire to the taillight area. That will be the ground for your relay.
-Run a wire and connect it to the (+) on your lights to the taillight area.
-Connect (-) on the lights to a bolt on the frame. It can be the same one you used as a ground (-) for the relay ground, but doesn't have to be. This will be the aftermarket reverse light ground.
-now, grab your taillight assembly. Look to where your factory reverse lights are in the housing and you should see two wires that go to the reverse light bulb. I don't know offhand what colors they are but ground is usually black/white and (+) is something else like blue, etc.. Take your Posi-tap and connect the sharp pointy side of it to the (+) wire of that reverse light bulb. Then take a length of wire and attach it to the other side of the Posi-tap.This becomes your trigger wire and you can set it aside for now.

3rd step:
-you should have 4 wires routed to the taillight area, one from the battery, a ground wire, a trigger wire and a (+) out to your new lights.
-take your fused battery wire, trim the wire to appropriate length and connect it to terminal 30 on the relay with a female spade connector.
-take your (-) ground wire, trim the wire to appropriate length and connect it to terminal 85 on the relay with a female spade connector.
-take your taillight trigger wire, trim the wire to appropriate length and connect it to terminal 86 on the relay with a female spade connector.
-take your (+) from your aftermarket reverse lights, trim the wire to appropriate length and connect it to terminal 87 on the relay with another female spade connector.
-all wires should be cut to appropriate length and all attached appropriately to your relay.
-mount the relay
-route and zip tie all wires.
-Insert fuse in fused wire and enjoy your new backup lights!

 

@DesertRatliff you are the man, thanks!

 

Happy to help. I edited a bit for clarification but it's helped me in the past to lay everything out on a sheet of cardboard and draw it out, the battery, the lights, the relay and the grounds. Once that's done, I feel it becomes pretty self-explanatory. Good luck!

 

@Freeheelbillie, I wired mine to include a 3 way switch int he cab to turn them ON (w/reverse lamps), OFF and ON (when I want extra light.) If you want to go that route I have a simple diagram adding the switch to the above diagram.

 

That would be sweet, share away!

 

Easiest way I know to add a switch is take the relay ground wire and put a switch in-line. You'd have to run the ground back to the cab for the switch to be operable there but that's no biggie.

 

The relay is the same if you forget about the extra tab(87A). For location #3 on the switch, I tapped into the R signal in the cab using a wire behind the kick panel behind in the drivers footwell. Can't remember the exact location right now though.

 

For argument sake;
Couldn't I run power from the trailer harness and splice into the reverse tail light?
Deleting the relay and fuse?

just running one of these https://www.superbrightleds.com/mor...fog-light-3-square-13w-1700-lumens/3542/7536/

 

Ultimately, the most simple method to get a lamp to work is to tap in to the reverse light (+) wire and ground the new lamp to the chassis. Done. However, 13 watts adds a little over an amp to that circuit (2.16amps if you add two of those lights). Could the reverse light circuit hold up to another amp or two draw? Off hand, I'm not sure so it's your call.

As for me, I usually say "why risk it?" and just add a separate labeled circuit from my Blue Sea Systems fuse block. It's clean, gives me peace of mind and makes trouble shooting 10 years down the road so much easier. But it's your truck and your project, so I say do what you want and give'r!

 

Totally agree. I was just trying to simplify (of course that can make issues down the road)
I prefer not to have to run power to the battery for one light...
Can I grab that power from the trailer harness and still run a fuse and relay?
If so how?
I am an electrical moron...

 

Toyota made the idiot move to tie the unfused reverse light circuit (including trailer reverse lights) into the IG1 fuse. Ig1 fuse is essential for a lot of things. So, when there’s an overload in the reverse light circuit, it blows IG1 and lots of stuff doesn’t work. It would have been much smarter to tap in upstream from IG1 and then have a dedicated reverse light fuse. However, even though IG1 feeds a lot of things, most of the things are very low amp draw triggers. IG1 is a 10A fuse. I’m sure nobody outside of Toyota engineers has added up all the current draw of all the circuits that it feeds. However, they did make provisions for lighting 2 reverse lights in the trailer connector. I doubt it’s printed anywhere, “Do not exceed X amps draw from reverse light trailer circuit”. An incandescent tail light draws 8 watts. A tail light bulb would make a pretty piss poor reverse light. So, Toyota would have to had to make the trailer reverse circuit capable of at least 16 watts. Now, if you want to play it on the safe side without going to the effort of wiring in a relay, put in Deauto LED reverse lights and then wire up your single pod to the trailer wiring.

 

Also, plenty of people put the home and garden bulbs in the reverse lights and nobody insists a relay is necessary for that mod.

 

I am currently running Philips 30w gy6.35 HIRs: 750 lumens reverse bulbs.

 

So that’s 4 amps on a 10 amp fuse with a whole bunch of other stuff. I definitely wouldn’t add 1 more amp. If you want to keep the HIRs, you need to put the pod on a relay. There’s another thread like this where Caribe shows how to wire in a relay using only the trailer wiring.

Note that some where in the 2nd gen run, Toyota changed the trailer wire colors.

https://www.tacomaworld.com/threads/wiring-a-single-led-pod-for-reverse-light.658007/#post-22969088