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A fairly common modification for TJ owners is the addition of front and rear lighting on the vehicle. Some decide to replace/supplement the stock backup lights with a pair of 55 watt after market lights. When this is done, you need to add a relay to the circuit to control the higher wattage lights. The stock wiring is not up to the task of controlling 110 watts of 12V light. If in doubt, check out this write-up and the problems encountered.
When the new lights are added to the rear bumper area, some folks realize that they would like to be able to turn these new backup lights on at times other than when the vehicle is in reverse. This comes in real handy when you need some extra light from the rear of the vehicle when performing trail repairs or making camp after sunset.
The following is one method you can use for your wiring project.
The above wiring diagram provides you with two methods by which to control your vehicle's new backup lights. When the Selection Switch is in position 1, 12 volts is applied to the power relay's coil and causes it to energize. The 12V on pin 30 is applied to pin 87 and that 12V is then applied to the new backup lights.
When the Selection Switch is in position 2, the relay operates in the same manner as just described. The difference is that the 12V to operate the relay coil comes from the vehicle's backup light switch. As such, the new backup lights will only illuminate when you shift your transmission into reverse. (It should be noted that the vehicle's ignition switch would need to be in the on position.)
If you want to fully disable the new backup lights, make sure the Selection Switch purchased is of the ON-OFF-ON design. (also known as a single pole double throw center off switch) Placing the switch in the OFF position would allow neither circuit to energize the relay's coil. This may be beneficial if you state has a vehicle inspection program which requires your stock backup lights to function as delivered from the factory.
I can't guarantee that your vehicles fuse panel and wire colors are the same as those on my '98 TJ. Some things do change over time....but here are a couple of things that may help make this project a little easier.
Enjoy your Jeep and remember to TREADLightly!