Before I start, I appreciate all the help you guys have given me already. I am looking for a little more insight into my problem. Ill list the facts as I know them:
1. My brake lights do not work, however the switch gets power in and both switch wire outlets are throwing out 12V as they should ( I would assume then that the switch is good ). Also, all the fuses in the fuse box are working and have power as they should.

2. My left turn signal does not blink (steady light), but the passenger side does.

3. When the headlights are on, the drivers side rear marker light comes on, but when making a left turn the marker light does not come on.

4. At the wiring harness at the rear of the trunk, there are several colored wires that go thru the frame of the trunk into driver side tailight assembly. I have determined that yellow is for turn signal operations and brown is for headlights. Both sides of the harness test ok for headlight and turn signal operations at the prospective colored wires terminals.

5. Coming from the harness is one major black wire, this I assume being the ground wire. It is connected to some type of metal connector which is then bolted into the trunk. It seems to have a good clean connection.

6. The sockets for the bulbs themselves each have a brown, black and a yellow wire connected, with the exception of the leftmost socket of the two on the driver side, which has 2 yellow wires and a black and a brown. Is this extra wires possibly for the turn signal operation? I have replaced the bulbs in the sockets twice to no avail.

I know I am real close to pinpointing the problem, yet cannot find it. I apologize for the length of this post, but I felt it was necessary to give you guys the most info that way you could better know the problem and possibly provide me with a solution.

I find it confusing that power gets to the sockets for the tailights to come on with the headlights, but not the brake lights. Far as I know, there is only one ground per socket for both brake a tail light functions.

Well there it is, once again Im sorry for having you guys read so much. My next option is to buy two more rpelacement sockets from Autozone and splice them in hoping the socket itself is bad. Thank you in advance for any help you guys can give me.

 

I'm assuming this is a Firebird; if it was a Camaro, the turn signal bulbs would be completely separate from the tail light bulbs, as the Camaro has yellow blinkers where the Firebird uses the same bulbs for both.

6. The yellow wire is the turn signal, and the brown is tail lights. The reason there are 2 yellow wires on that socket is because the wire comes in from the dash, goes to that bulb, and then continues on to the next bulb. You will note that the right sight sockets are prety much the same, except that the right blinker wire is green.

5. You are correct, the black wire is ground. You should check the shell of the bulb itself with the tail lights on and make sure that it does not have 12V on it when the tail lights are on, which would indicate that the ground wire or the ground part of the socket is broken.

4. See #6.

3. One or more of the bulbs on the left side of the car is in its socket wrong, or the ground side of the circuit is not working. You don't say, but the behavior of all this (which lights do or don't work) probaly changes when you turn the headlights on, which if so would definitely point to a ground connection being open.

2. See #3.

1. You don't say, but I'd bet you actually have right brake light but not left. I think when you get the rest of this fixed, this will clear up.

Good luck!

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"So many Mustangs, so little time..."

 

I agree with the wrong bulb theroy. One or more bulbs are drawing the rest down, sucking up all the power.

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87 Z28 305 TPI, Auto, 2.73, Gutted air boxes, K & N fillters, Dyno Max 3" cat back, Accel 8.8 mm spirals, Accel cap and rotor, Accel coil, rapid fires, and 160 Stat.
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