My 1996 Volvo 850 recently failed inspection due to a number of issues (as usual). Among them was the failure of my third brake light. Replaced the bulb, tossed it, and put a new one in. Tested it to make sure it worked, and it did... the first time I pressed the pedal. Wouldn't work afterwards. Now, every time I get in the car, I take the assembly apart to see how long I can get the light to work for. It ranges from not functioning at all, to working for several minutes of pressing and depressing the brake pedal.

I messed around with the light to make sure it was in correctly. Checked the wires that I could get to without much trouble (ie. not the ones in the trunk), and they all looked fine. I even tried sticking another replacement bulb in, but I keep getting the same results.

Any suggestions?

 

check the switch that is on the brake pedal. that may be sticking thus not turning your brake lights on at all.

if thats not the case put a volt meter on the brake light and see what it reads and report back.

 

The Brake switch can be ruled out if your other brake lights are comming on consistently. Just clean the contacts inside the holder with some emery paper before you throw in the bulb.

 

It's definitely not a fuse or the brake switch. The two regular lights still turn on.

And one of the contacts did look a little dirty, but I figured it wasn't a big deal. I'll try cleaning it soon.

 

Once you get it clean put some bulb grease on the bulb before you reinsert it. Keeps the corrosion down and gives you solid contact.