Check the bulbs in case they have fused, next check the fuse, and finally it could be the brake light switch which may need replacing
check your fuses
It should say TAIL for taillights or maybe brake lights.
They aren't. The brake light circuit is not connected with the headlight circuit.
replace the lamp socket they short in a strange way, it happened to me 3x. the socket carbonized from bulb heat
brake relay or sensor
my fuse panel (with the descriptions) is gone off of my 2000 jeep grand Cherokee Laredo, how to i get a description of what all 32 fuses control on my jeep?
Yes. They work fine if the lights are off (ie. during the daytime) but when the lights are on all the brake lights are off. Our Grand Cherokee has tons of problems. The ac sometimes does not work, the gauges go crazy, the power windows play dead sometimes. We got it checked out. Mechanic says our body control module is going bad.
this sounds like a fuse or 2. that's where i would start.
How to change the brake switch on a 2004 Jeep grand Cherokee Laredo
This is a common problem with that car. It is caused when the ground connection on the brake/taillight socket stops making full contact. The official way to fix this problem is to replace the taillight assembly, but the way I fixed mine was to slightly bend up the ground connector inside the taillight. The ground is the tab that's by itself (there are 2 others that are together). VERY gently with a tool, pry the metal so it's bent a little upwards. This will allow it to make contact with the socket again. You have to be very delicate because it's fragile. It doesn't take very much effort to bend. I tried this and it worked great! Thanks for the info.
Check the bulbs in case they have fused, next check the fuse, and finally it could be the brake light switch which may need replacing
You need to check the wiring for power to the bulbs.