Cant figure out why 3rd brake light wont work

[TABuickMike]

A friend told me that the third brake light in my T-Type wasn't working so I took it all apart and replaced the bulb (which was burned out) but it still doesn't work. I cant figure out why, the bulb is in the socket properly and its a brand new bulb, what would be the next thing to look for?

Thanks

 

[boostingbuick]

Use a test light to see if you are getting a 12v when hitting the brakes. If you are not there is a diode pack in the rear lamp harness that maybe bad. If you are, than the ground my be loose or dirty.

 

[TABuickMike]

there is a diode pack in the rear lamp harness that maybe bad

Where would the rear lamp harness be? >.<

 

[gnxtc2]

Try your brake switch.

There are 3 wires on the brake switch. I think its blue, black and some other color. The switch has constant 12v then one of the wires goes to the rear tail lights and the other goes to the 3rd brake light.

Billy T.
gnxtc2@aol.com

 

[turbofish38]

If you are not there is a diode pack in the rear lamp harness that maybe bad.

I don't think our cars use a diode.

Most likely you need to replace the CHMSL. The major problem is that the socket is made of plastic and much like any 22 year old piece of plastic it will crack. Let me say this. I don't have to much luck finding decent used ones in the cars we part out here anyway.:frown:

 

[Roger]

The high (per Buick) brake light is the only thing feeded from the brake light switch. The other switch feeds everything else (cruise, tail brake lights, computer, etc).

I had to clean the contacts on my switch to get it to work. I also am using led bulbs to reduce heat damage in the light fixtures.