Where to tap-splice for aux reverse lamp?

Se7enLC · **Posted:** Mon Aug 20, 2012 10:50 pm

Does anybody know where to grab a reverse wire in the dash? I'm trying to wire up auxiliary reverse lights and I want to splice in by the switch instead of by the reverse lamp.

kjon · **Posted:** Tue Aug 21, 2012 12:04 am

Are you saying that you want the light to turn on anytime you put it into reverse? If so, you'd have to splice into the wire that runs the stock reverse lights, and I don't think that would be recommended due to gross differences in power requirements. If you're using garden variety fog/off-road lights, I'd hook em up to the battery and run a switch to a convenient location on the dash. I'm no electrical engineer, but I wouldn't risk frying my electrical system.

dgeist · **Posted:** Tue Aug 21, 2012 2:27 am

kjon is right about not just splicing into the power to the lamps. Unless you have a VERY small load you're adding, putting additional lamps on factory wiring is ill-advised. Since you're putting it in under the dash anyway, what you want to to run new (appropriately sized) power from one of the fuse panels and tap the trigger for the relay that the reverse lights are using. That way, the same low power signal from the computer (or perhaps the tranny controller if you're an automatic) will trigger current and new lights. The other benefit is optional "on" states like having a toggle that either has the lights in "on" or "auto" mode, so that you can leave them on for a while at a campsite, but when driving, have them follow the behavior of the factory lamps.

I'm not sure of which relay you need to use, but EurekaBoy has a really good writeup on his here:
http://liberty.eurekaboy.com/reverselights.htm

Dan

spitfire36o · **Posted:** Tue Aug 21, 2012 9:39 am

I am going to assume that he was referring to where to pull the 12v to activate the 30 amp relay (that's the relay needed - radioshack has them)
As far as the wire at the switch, I haven't found one. I ran a wire from the reverse wire in the hitch plug up to the front (under the jeep) and in through the firewall when i wired up my reverse camera.

dgeist · **Posted:** Tue Aug 21, 2012 11:50 am

I think the factory reverse lamps may actually be powered from the signal line (grey/white in the trunk right access panel) and not be relay driven. It might make sense to tap it there since that cavity already has provisions for relay mounting, etc. Ultimately, though, it depends on where the switching for the relay is. If it's just that lead, then put it in the trunk and forget it. There's a 30A power lead for the trailer wiring (hopefully you have that) there already, or you can pull a new one. If you want it to be switch-controlled (or possible SPDT for multi-function behavior) you might need to run a small bundle of low-current wires back there to support a couple relays in parallel or series depending on what your intended behavior is.

Dan

At The Helm · **Posted:** Tue Aug 21, 2012 2:23 pm

Se7enLC wrote:

Does anybody know where to grab a reverse wire in the dash? I'm trying to wire up auxiliary reverse lights and I want to splice in by the switch instead of by the reverse lamp.

I used this diagram for mine. Works well and i can turn on all four lights anytime i want. Keys dont even need to be in the ignition. I skipped the diode though because it gets red hot. Installed for alsmost 2 years and no problems.
http://www.phildorsett.com/backuplights.html

Jeepin'WNC · **Joined:** Mon Nov 15, 2010 1:48 am **Posts:** 191

I wired a simple connection straight to the battery, with a fuse of course, up to the center console cubby, then through a toggle switch back to my additional reverse lights that are mounted to my frame hitch. I used a lighted toggle, and the ground for it is just underneath the driver's side kick panel, on an already existing ground lug. I couldn't love it more; it's simple it works with the ignition switch off, and it's great for hooking up my camper or boat at night. My fuse holder is a large enough gauge that I'm eventually going to tap into the same circuit for a two pole flat connector for reverse lights on the rear of my camper, to help in backing it after dark. The wiring for my reverse lights runs through a channel that is in the driver's side floor of the Liberty's, underneath/behind the trim in the cargo area, and out through a hole drilled in a factory drain plug that is on the driver's side above my frame hitch....

Se7enLC · **Posted:** Wed Aug 22, 2012 2:29 pm

Thanks for all the comments.

Of course I'm not going to POWER the light off the reverse wire - I just need access to the signal to switch a relay. I'm well-versed in how to wire up the relay and all, so this is really just a question of where to physically tap to get access to that signal.

I can, of course, tap right at the rear light - but then I'd have to run a wire up the the dashboard, switch it, and run a wire BACK to the rear to trigger the relay for the light. I was thinking that there must be a wire up front, I just can't find it anywhere! If anyone has detail on which wire it is, please let me know. I've looked for a "white+grey" wire, found quite a few, but none of them switched with the reverse light.

Where to tap-splice for aux reverse lamp?

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