does the lights in the rear trunk lid next to the back up lights light up when the brake lights are applied?

 

What Make/Model/Year is your vehicle?

 

If talking about a face lift XJS.
No...not brake lights unless so rewired.
They are the rear fog lights. Simple to find out.....Do you have a rear fog light switch next to the front fog light switch and a light on the dash when on ?

 

They are rear fogs on my 92 US spec car..... I know this because I had to take them out last night to drill holes in my trunk lid to fit a trunk spoiler..... hopefully I drilled the holes in the right place

 

yes it is rear fog lamps..