Gf's focus -brake lights

Hey guys, so my gf has an 01 ford focus. I was driving behind her the other day and noticed her brake lights aren't lighting up. the tail lights are on, and brighter than they should be, but when she brakes they don't get any brighter.
today we checked light bulbs, and fuses, but found nothing, my next though is a relay, but I'm not sure on how to test a relay?
what else would you suggest? thanks!

 

does the third brake light go on?

 

If the tailamps are on and brighter than normal than the bulbs may be incorrect. Check those..

Does the cruise work??

If not check the brake lamp switch under the dash.

 

I'm going with the bulbs are in backwards. Seen this 1,00 times on semi trailers. there are two posts on the side of the bulbs, One is father from the base of the bulb than the other. the bulb should be inserted to the socket according to which hole is relevant to the posts on the bulb.
not saying that is definitely it, but worth a shot to look.

 

yea, a buddy said prob the brake switch. i'll check bulbs too. thanks alot