Brake Lights Do & Dont work--help

[carguy24]

Interesting situation here...During day (when headlights are off) and I depress the brake pedal, the brake lights come on. At night (when headlights are switched on) the rear lights are on and visible, however when I press the brake pedal, they all go off. The only light that works is the 3rd light on top. Any ideas or fixes? Already been stopped once and if there's another way other than letting someone see it for $85 diagnostic and then parts and labor, I sure would appriciate it.

2000 Jeep Grand Cherokee Loredo

Thanks

[carguy24]

Ok, I bought a switch and installed it, only to have it work the opposite -- Switch out, lights on, switch in lights off... Long story short, I returned it and reinstalled the old switch which now gave me at least one brake light.

-After all that I know on trouble shooting this matter, I came to the resolution that a trailer hitch that was installed before I purchased (jeep-was used) has the wiring hooked into the left tail light via a junction box or a "5 amp circuit Protector/ Tail light converter" by Curt Manufacturing Corp. The odd thing (at least to me) is that once again when the headlights are off, all brake lights work, when the head lights are turned on all but the left brake light works.??? Any ideas on how I could test this little black box???? Somebody? Anybody??

Thanks

[dksob81]

check the connector for the Trailer Harness. I seen someone had a problem with there Turn signal coming n when they hit there brakes and it was caused by dirt or something in the wiring harness, I'm sure yours is prolly the same.

[Cam7]

Check the connection at the trailer harness or try disconnecting the trailer wiring harness and recconect the original wiring harness it seems there is a short somewhere probally in the light section of the harness.

[Bad_Wing]

My 93 Grand Cherokee had a wire worn where it exits the body and enters the right rear light housing. This short did not blow a fuse, but made my lights act very strange, similar to yours. My suggestion is to check all bulb sockets and wiring for the rear lights. Make sure none of the bulbs inserted incorrectly. Try unplugging a harness and checking to see if the opposite functions correctly. Good luck!