First, If aftermarket lighting (Not Stock) and the lights are not working I would have to question if the wiring was any good.
IMHO... Remove any existing wiring and replace with new wire, relay, in-line fuse and dash switch.
First determine the wattage of the lights, it will make a difference in the fuse and the gauge of wire you use.
Then wire as follows:
1) Mount a Relay (amperage rating dependent on wattage of lights) in the engine compartment close to the battery area.
2) Run a 12-ga wire from the battery to an in-line fuse holder (amperage rating dependent on wattage of lights) then to Pin 30 on the Relay.
3) Run a 12-ga wire from pin 87 on the Relay to the lights.
4) Ground the lights. Some lights ground through the housing, some through an additional wire but the best is the additional wire since you can get to a good bare metal grounding point on the frame.
This will give you the power you need for the lights once the Realy has been activated.
To activate the Relay continue:
5) Run a fused (this fuse can be a low value because there will be minimual current here) 18-ga wire from the Fuse Panel to one side of a Switch mounted somewhere you like.
5a) This wire should be connected to one of the following types of power at the Fuse Panel:
"Power on all of the time" - usually directly from the battery but through the Fuse Panel or "Switched Power" when the ignition is turned on - use a mutlimeter or DC Voltage Detector to determine that you have power when the key is in the on position. You choose which type of power you want.
6) From the other pin on the Switch run a wire to Pin 86 on the Relay.
7) From Pin 85 on the Relay run a wire to a good bare metal gorund point.
When you flip the switch the relay should click and the lights should come on.
This is simplified but it should work.
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