Automotive Forums

Hi all, I need help trouble shooting a problem with my 99 Jeep Grand Cherokee Limited. The driver side brake light is acting up, when the headlights are off the brake light looks dimmed and when the headlights are on the brake light doesn't work at all, but the tail light (I think they are the same bulb) does.

I tried replacing the light bulb but that didn't fix it. Does anyone have any ideas as to what the problem might be?  

that kind of thing would happen to small trailers hooked up to a car. you would turn on the headlites of the car and the tail lites of the trailer would also go on. But step on the brake and not only wouldn't the trailers brake lites go on but the tail lites would also go off, so there was no lite back there at all.
The cause of this was a bad ground between the car and the trailer. If you have a bad ground wire on the back lite it will do much the same thing.
Look at the lits plug and make sure it isn't corroded. If thats ok then scotch cip a pice of wire on the taillte ground wire [sorry i dont know which color it is and run it to the neg terminal of the battery. Now if that cures it then find a good piece of metal ground in the trunk somewhere and screw the wire in,
the reason i said go to the battery for the test is because new cars have a lot of plastic everywhere and we have to be positive for the test.
If thatsw not it come back and we'll think something else up.because then its something else.  

If I remember correctly there was some corrosion on the socket were you plug the bulb into.  

There is probably your answer. Change the socket with a new one.