Jeep Cherokee Electrical - Halogen Reverse Lights Upgrade "How-To" guide.

Dump those wimpy reverse lights!

Tired of squinting while trying to back up with the puny stock reverse lights? Time to fix that and light up your rearend at the same time!

My stock reverse lights never were very bright to begin with and after years spent squinting while backing up, I finally checked things out with a voltmeter. When I did this, I found that I only had 9.6 volts going to them! No wonder they were so dim! The simple fix would be checking accessable harness connections and adding a ground jumper to help get the voltages closer to 12volts which brightens them up a bit. Check your bulb voltages out but don't be surprised if your voltages are low too. This is not really surprising when you take into account years of oxidation to harness connections and chassis grounds and the innumerable connections along the harness that are strung along the length of the body. No sweat though! We're going to just use the stock light circuit to control our add-on rear view retina burners!

You should be aware that if you wire these up to an auxiliary switch you will be able to turn these rear halogen lamps on at any time!

IF YOU TURN THESE ON WHEN ANOTHER DRIVER IS BEHIND YOU THEY WILL BE UNABLE TO SEE THE ROAD AND MAY CRASH!

Law enforcement personel tend to take a dim view (A pun! Get it? ) of people deliberately blinding tailgaters, a$$holes driving with high beams on or anyone else behind you for that matter.

Also be aware that PEOPLE WITH GUNS do NOT need to see the road... They only need to see well enough to draw a bead just above and between your two 'reverse' lights.

DO NOT USE THIS MOD AS A TACTICAL STREET WEAPON!

What do ya want?

There are a couple of things to consider before ya start. First, do you want the auxiliary back up lights to come on ONLY with the stock reverse lights or do you want to be able to switch them on ANY time as well? Being able to switch them on at any time gives you the ability to use them as 'cargo lights' when hooking up trailers or working behind your rig at night.

Secondly, where do you want to mount them? Just be sure that they'll be out of harm's way and not where the casual passerby will contact them if they've been on and are hot. Consider also that an encounter with a tree stump can break, or drive them into the body of your rig if you don't plan their location well. Take a few minutes to consider your mounting options and location.

Those are decisions you'll have to make so I'll just cover both ways of wiring the lights up and leave mounting locations to you. I'll provide a few pics of my lights to help you along. Your situation will be close enough to mine to grasp the general idea.

Note: The manual switch circuit REQUIRES the listed diodes to prevent shorts due to OEM harness interconnections with the Neutral Safety Switch and the Transmission Control Module. If you use the manual control switch you MUST use the diodes!

EITHER WAY YOU WIRE THIS MOD REQUIRES the listed relay! Your stock back-up light wiring harness is NOT capable of running hi-wattage lights for sustained periods and tapping directly into it for hi-wattage lights WILL FRY YOUR WIRING! USE THE RELAY!

What you'll need.

Tools to beg or borrow:

Drill and set of bits.
A GOOD soldering iron and solder.
A digital volt-ohm meter.
Wire connector crimping tool
Assortment of crimp connectors & ground lugs.
Inline crimp on 'wire taps'. (For tapping into existing circuits without cutting wires).
Some sheet metal screws that will fit your crimp-on ground lugs.
Roll of 16 ga. red wire. (Buy a 100' roll and save the extra for other projects!)
Roll of 16 ga. black wire (Same advice. No, you won't use much of this... today).

Parts for lights that work with back up lights AND are switchable:

General Purpose Automotive Relay	Under $5 at Advance Auto
* TOP MOUNTED * Lighted Rocker or Toggle Switch (single pole, single throw)	About $4 at Advance Auto
2-pack of Rectifier Diodes 3 amp, 400volt Radio Shack # 2761144	$1.49 at Radio Shack
Halogen or other driving lights that will suit your application. Check out Northern Hardware - Item# 18816 - 1 pair of lights for $9.99! Click here for a direct link to these lights on their website.

* - Top mounted (surface mounted) switch was used for MY application. You'll need to determine what kind of switch you want to use.

Left to Right - Relay, diodes, rocker switch. Northern Hardware lights, Item# 18816 are a bargain at $9.99!
Click here for a direct link to these lights on their site.

Here's the basic schematic for wiring your lights up WITH the manual control option:

Basic schematic for wiring up aux reverse lights with manual switch

A few tips for those who may be a bit inexperienced with electronics or wiring.

First, if you lay things out, literally, as the schematic is drawn you'll see how things will go without too much trouble. If you wanted, you could wire up the switch, diodes & relay up front and run all wires to the back from there but you'll use a bit more wire. I chose to locate the diodes and relay in the rear quarter panel next to the tail light assembly.
The two 'dots' labeled "SPLICE" are exactly that; places you will splice two wires together. In one case, you will SPLICE into the factory back-up light wire running to the reverse light bulb and in the other instance you will SPLICE into the new wire to the relay from your control switch.
Diodes aren't hard to comprehend if you'll think of them as being a 'one way' gate that allows electricity to flow ONLY one way. The schematic shows some triangles with a line drawn across the end. The triangle can be thought of as an 'arrow' pointing the way for electricity to follow and the line as a gate that only opens in that same direction. Just as in the diagram, actual diodes have a line painted around them that indicates the direction of current flow and indicate which end voltage will come out of.
Relays aren't a great mystery to understand. Just think of a relay as a remote switch that your Neutral Safety Switch or toggle switch will send voltage to. That voltage in turn causes the relay solenoid to activate a seperate, internal, heavy duty circuit to send voltage to your auxiliary lights. See RELAYS for details on wiring these.
The above circuit shows the Aux Light's supply coming from a 15 amp fused source. I have a small Auxiliary Fuse Box under the hood which is fed directly from the battery and has 6 seperate circuits. Such fuse boxes are an excellent way to add on those extra lights without cooking the stock fuse box or running a rat's nest under the dash.

Parts for lights that work ONLY with back up lights:

Relay - general automotive use (most are 30 amp relays for fog lights,etc.)
A set of driving, or fog lights with adjustable bases. Recommend 50 watt max.

Yup. Fewer parts and a bit easier to wire. If all you want is a set of extra lights that turn on when you back up then this is the way to go. Pretty much self explanatory, this circuit connects the relay to your reverse lights (as above) but does NOT include diodes or a manual control switch.

Schematic for wiring up aux reverse lights withOUT switch.

Get Started!

Switch Location.

Just make it convenient to use and where it won't be damaged by accident.

In my case, I have mounted several switches on the cover surrounding the shifter to control rack lights, tranny control etc. This location is harder to set up due to the shifter needing plenty of room to operate. If you do mount your switches here you MUST CAREFULLY ROUTE all wires and space your switches up high enough to clear the shifter mechanism! The shifter needs plenty of room between it and your wires and switches or you'll be cutting wiring up with the shifter and possibly interfering with the shifter's operation! No sweat, this is only one of many places to mount your switches, or you can just use the switch panel usually included with most fog light sets.

Omit center two holes if you are NOT using a spacer under the switches..

If you want center console mounted switches without the hassle of interference issues... Craig has a neat installation idea for switches that will allow a more 'trouble free' installation. His idea uses rocker switches in a small add on switch panel that looks like a factory installation. Check out his idea for switch mounting here.

Remove your driver side tail light lense.

Use a 10mm socket and extension to remove the lense assembly. Carefully tilt it away from the body and you should have enough slack in the wiring to lay the lense flat on top of the bumper, or a cardboard box set up at the bumper.

Remove tail light lense.

Locate your oem back-up bulb. Set the parking brake, or better yet, have a friend hold the brake and shift into reverse long enough to locate the correct wire. (Do NOT leave the vehicle out of park!) Now trace back the positive (hot) lead going to the center of the bulb's base and select a location to splice into. A digital volt meter comes in handy if you have difficulty here. Just find the power feed going TO the bulb. Mark it with some labeled tape if you need a little help keeping track of things.

Locate and tap into back up light lead going to reverse light bulb.

You can splice into the circuit a couple of ways. One is to strip a bit of insulation from the oem back-up light supply wire and solder the connection. Another is to use a crimp-on wire splice/voltage tap. Since this is not a sensor circuit and this connection will be well protected from the elements, I used a crimp on voltage tap. I wired up the relay and diodes were soldered into the circuit as shown in the schematic. I then wrapped both the relay terminals AND the diodes with heat shrink tubing and some electrical tape. You can't see the diodes in this picture but they're inside that bit of extra thick tape going to the left most terminal of the relay. The diodes don't care if they're close to the switch, close to the relay or close to each other just so long as they're wired properly.

Here is relay tapped into circuit. Diodes are soldered into circuit and wrapped up.

Double check that everything works then wrap everything up for a few inches down from the relay to protect the diodes from damage should the wires get yanked by accident. I fed the new wiring inside and just zip tied the relay into place for my mounting location. Location shown is visible through the tail light lense opening on the back.

View of relay zip tied inside area behind rear driver side lense.

Mount your lights!

I chose to mount my lights on the 'ears' of my air tank bumper. You can mount them wherever it is convenient and safe, even up on your roof. Just take the time to properly route wiring away from potential damage and mount the lights where they won't get broken or burn anyone. I fed the 'hot' lead over from the other light by running it underneath the plastic trim where the latch is mounted in the cargo area floor and fed it down by temporarily removing the tail light lense.

Old Harbour Freight Lights
Passenger side light in place.

Old Harbour Freight lights... Big & clunky... but cheap! Plastic housing & mounting sucks though.

New Northern Lights

New Northern Hardware lights. Fit beneath stock light assemblies, all steel & are just as bright as the crappy H.F. lights.

UPDATE! Northern Hardware lights... $9.95 for the pair!

Just mounted these to replace the big ol' clunky ones from Harbour Freight. These are a bargain at under $10 for the pair and with my bumper they fit PERFECTLY beneath the rear light assemblies and are out of the way!

Pictures don't do this mod justice, you'll just have to see it for yourself when you do yours. In my case, the clear lense driving lights I used appear 2x as bright as the stock headlights! Wattage is the same as OEM headlights (only 55 watts each) but these lenses don't have the 'waffle' design that helps disperse the light for oncoming traffic making them real retina burners if you're not careful!

A LOT brighter than before!

That's it! Start backing up everywhere ya go now that it's easier to see where you've been.

In the interest of keeping those with attention deficit disorder alive... I'll repeat it again, just to make sure:

IF YOU TURN THESE ON WHEN ANOTHER DRIVER IS BEHIND YOU THEY WILL BE UNABLE TO SEE THE ROAD AND MAY CRASH!

Law enforcement personel tend to take a dim view of people deliberately blinding tailgaters, a$$holes driving with high beams on or anyone else behind you!

Also be aware that PEOPLE WITH GUNS do NOT need to see the road... They only need to see well enough to draw a bead just above and between your two 'reverse' lights.

DO NOT USE THIS MOD AS A TACTICAL STREET WEAPON!

If you have pics of your own repairs or can suggest other methods - please contribute your ideas (and pictures) to this article!

Revised on: January 28th, 2008