I do a lot of towing with my '99 4-dr and sometimes end up backing into driveways or campsites at night with a 18' boat attached. I want to add additional lighting below the rear bumper that comes on when I put the vehicle in reverse.

I know there is a wire in the trailering harness that provides 12vdc when the vehicle is shifted into reverse, but I don't know how much current is available. I think the wire is only 18 or maybe 16-gauge. I don't think this is hefty enough for a single, let alone a pair of spare halogen (H4 bulb?) off-road lights. It may be enough though to trigger a relay.

The last set of halogen lamps I installed was nearly 20 years ago on the front bumper of a Bronco II. At that time I used a 15A relay for the high-current side. Other than issues with the relay getting wet, it worked fine.

Anyone out there with recommendations on how to get some large-gauge wire from the engine compartment to the rear bumper on a '99 4-dr? I'd prefer the wire protected from both mechanical damage and the elements, so I imagine going through the vehicle is my only option. Any ideas? Also, is this something that should be connected to the battery directly or is there a better place?

packrat

 

I have a receiver mounted set up from Bully Dog I think. They clip into existing wiring & can be set to On, Reverse On & Off, only when the vehicle is running of course.
They do a decent job of lighting up directly behind me but I'd like a wider light spread. I've seen a couple other brands on the net that are aim-able & wire directly in much the same way.

You could get a pair of halogens, mount them where you like & run a 10G wire to a relay mounted somewhere safe & have it activated by plumbing into the reverse lights' wiring.
Get under the vehicle & see what would be a safe way to run a wire (with a fuse inline) to the rear. With all the holes in our frames I don't see why you can fish a wire through the frame & protect the entry & exit points with grommets or lots of electrical tape around the wire.
Also you have have the activation side of the relay on a switch in the cab so you can have total control if they're on when in reverse or on when you want them on.

 

^ X2 I have my backup lights on a SPDT switch for the on-off-reverse on, function and a relay of course. Then I put 55w hids in them to really give me some extra light when I am backing up (and to discourage tailgaters ).

 

55W HIDs for backing up?! Holy chit that's bright for going backwards!

 

Why not mount a relay inside the left rear quarter panel cover to protect it from the elements? If your vehicle is equipped with the trailer tow wiring package, there's already a 10ga battery feed under the rear bumper. Use the trailer tow reverse wire to triger the relay.

 

Bingo Hook lol

 

Really,

A 10ga trailer feed you say? I know there were extra wires in the bundle, but it's been so long since I wired up the 4-pin harness, I don't remember a 10Ga wire in the mix. I'll have to get under there an take the wire loom I put in apart. Having that wire already available will save me a LOT of headaches.

Yeah, I'll probably mount the relay in the back somewhere and have to wire up a switch to be able to keep it off when I don't want to blind anyone. I guess I'll still have to pass a small wire up to the dash.

Thanks for the input guys. Now I just need the time.....

Oh yeah, and a 12v coil 15A relay. Any recomendations?

 

In the underhood fuse panel: Stud 2* has battery voltage at all times from a 30A maxi fuse and a red 10ga wire going to the rear. I can't remember what color the B/U wire is, but it's back there too. You could actually put a SPST switch in that B/U wire and run the two wires up into the cab. The switch would disable your add on lights only.

* Stud 2 is in the inboard rear corner of the fuse panel. You'll need to install a fuse in the fuse panel, (it does not come with one).

 

I use 55watt fog lights as extra backups. I have 50 watt halogen 1156 base bulbs in the tail lights. The 50 watts are good enough 99% of the time so I leave the fogs off. They are wired up with a relay with a STDP switch like above.