Wires in rear body deck

[DonWheeler]

There are two wires (brown, and gray/black) protruding from the black wiring harness on the rear body deck. The wires are wrapped nicely (tie-wrapped) above the opening where the twin exhaust pipes protude through the body.
My question is, what are they for?
If by chance either, or both can be used to provide current for a lighted license plate frame, please tell me how to do it.
If they are not related to providing power to a lighted license plate frame, could some one tell me how I can provide power to a billet aluminum lighted license plate frame I just purchased.
And, if it makes more sense to respond in the relatively new "HOW TO" section of the forum, provide the instructions there.
Thanks.

[Big-Foot]

Don - I can't speak of what the true purposes of those wires are but I'd willing to take a guess..

Use a test light between the conductors of those two wires and turn on your headlights. If the light comes on, you've found the ground wire (gray/black) and the switched 12v (brown)..

If that doesn't work, try grounding one of your test leads and touch the other lead to the brown wire with the lights on.

If all else fails, you could splice into the taillight circuit to run your license plate light.

[Lynn Miner]

Don

Randy's comments are likely correct and as he notes, easy to verify. The early cars did not have these wires so I can't say for certain what they are for. Maybe license plate light, maybe rear deck roundle light. Either way it's simple to figure it out with a volt meter or test lamp. Brown is ground and gray/black will the 12VDC. This is the opposite of Randy's comments but I can assure you the brown is ground on SPF cars. Check out the posted schematics in the How To section. Connect your probes and look for power when you either turn on the driving lights or hit the number light switch. There is are "How To's" on both installing a license plate light as well as a roundle light already posted.

[DonWheeler]

Thanks guys for your comments. I will follow-up on your advise.

[DonWheeler]

I was able to use the two wires (brown is ground, gray/black is power) to allow the lighted license plate frame to operate. Don P/2171.