Electrical problem: dim brake lights

[YooperSkipper]

Just found a electrical problem on my newly acquired 02' TJ. Wife noticed it while following me home. Both tail lights are fine, but when I brake, the passenger side brake light goes dim! Today I removed the lens and tried again. Actually both the backup light and the brake light go dim at the same time. The bulbs looked OK. When I checked the turn signals, the passenger side works fine front and rear. The drivers side, however blinks real fast with both the taillight and backup flashing dimly. Any ideas where to start?

 

[ac_]

Just found a electrical problem on my newly acquired 02' TJ. Wife noticed it while following me home. Both tail lights are fine, but when I brake, the passenger side brake light goes dim! Today I removed the lens and tried again. Actually both the backup light and the brake light go dim at the same time. The bulbs looked OK. When I checked the turn signals, the passenger side works fine front and rear. The drivers side, however blinks real fast with both the taillight and backup flashing dimly. Any ideas where to start?

On the side that blinks fast that is usually someone introduced a LED in the circuit somewhere or you have a bulb out. I would check the grounds on the light housings. Once you pull the lens off there should be 3 bolts holding the housing on. At least there is on my older Jeep. Take those three bolts off and clean up behind the housings. My guess is that you got water and dirt behind the housing that is corroding the ground.

If is free and if it isn't the issue you know it is not the problem. I would probably also replace all of the brake and tail bulbs too.

 

[Jerry Bransford]

Likely a bad electrical ground connection at the tail light assembly. Under the red lens cover you'll see three hex-head bolts that attach the tail light housing to the tub. Those three bolts also provide the electrical ground connection for the lights. Try removing, wire brushing, and then reinstalling those bolts. Or at least a few quick loosening/retightening of those three bolts to assure they're making a good ground connection for the tail light housing. While you're in there remove the bulbs and reinsert them for the same reason.... their connections may be getting flaky.

 

[balfred]

I had this same thing and in the rear wheel well under the plastic cover I found the connector for the light to be covered in junk and it was corroded. Once the connector was cleaned and had new electric grease it was fine.

Sent from my SM-N950U using Tapatalk

 

[Ed Wright]

Same here... taillight on driver side was dim. When I would hit the brakes it would appear to go out.

I cleaned up and bought new screws and man did it brighten up the taillight. I even did my passenger side which didn’t appear to be an issue until I fixed the driver side.

 

[Flivver250]

+1 on bad ground.

 

[martinjg98]

You guys are the best. I already bought new bulbs and was thisclose to replacing the entire taillight assemblies with LEDs, but after reading this thread, I realized that it was just a bad ground due to incorrect screws. The previous owner had put on Euro tail light guards, but when you do that, you have to swap out the 3 screws with longer screws to accommodate the additional hardware. He must have just guessed at the screw type — they were too thin for the holes. $3 worth of correct screws later and I am good to go!

The most painful part was trying to figure out what the correct screw type is for the 3 screws. The YouTube videos on this are wrong, at least for my '99 Sahara. So just for the record, if you install Euro tail light guards and need to lengthen the 3 screws in each tallight, the correct screw is 12-4 x 1 inch Hex Washer Head machine screw with a self-drilling tip and a coarse thread. Unlike the bolts that hold the license plate frame in place, this is not a metric screw.