car is a 91 acccord dx.

saturday morning all brake lights work fine.
saturday afternoon, 3rd brake light (high brake light) does not work.
things that changed inbetween... i installed an amp + subwoofer and my 50/50 tail lights. i checked all my fuses, even the unrelated ones. they're all good. i used a test light to see if the high brake light was grounding properly and that seems good. i'm getting battery voltage to the high brake light connector, it is a little weak though @ about 10.9 volts. i originally had my amp grounded on the rear deck, but i removed it from there and grounded it under the rear seat. all the other brake lights work.

can anyone help out, i don't want to get pulled over or rear ended.

 

i've done some digging and found that it could be the brown boxes on the tail lights. can anyone reject or confirm this?

 

if there is power to the 3rd brake light lead wire (when u brake) your test light lights up...
and the bulb doesnt light up then check the bulb... if its not the bulb then its the ground assuming that there is power to the 3rd brake light.... stripe a little off the top of the ground add a wire and touch it to chassis and have some one step on the brake..

 

the ground is good, and it's getting power. i'm beginning to think it's the stop light failure sensor. i guess it malfunctioned or something. part #28/29 in the illustration. i'll mess with it today and see if anything happens. anybody else have any suggestions.

 

ummm, if your light has power and ground but doesnt light your bulb is blown

 

i believe i have a bad light socket, so i'm going to swap it out and see what happens.

 

im telling you, the bulb is bad if you have power and ground and the bulb doesnt light up, take an ohms reading on the bulb, your meter will read infinity or OL, no circuit

 

maybe something is getting messed up with the different brake lights

but the simplest thing would be to swap a bulb, i think all the brake lights and reverse lights use the same ones