I need to know which wire is which for the tach on my 86 camaro it has a 74 350 in it with a msd ignition hei distributor if someone could tell me the color of the wire for my tach that would be awesome or a way to check if its the gauge thats not working

Secondly the 3rd rear brake light at the top of the car wont turn on i think i may be missing the fuse for it if someone could tell me which one it is tjar would be of much assistance

Thanks for everything and if you can take a picture or video that would be perfect thanks so much )

 

The tachometer wire is white.

For the 3rd brake light, I would check the bulb(s) in the light first. It uses the same fuse as the standard brake lights in the tail lamp housing.
If you determine that the bulb is good but the light is not getting any power, it might possibly also be the switch on the brake pedal assembly.
Diagram here:

Let us know what you find.
Lou

 

Alright well its connected so why would it not work? Am i missing a fuse could someone take a picture of their fuse box so i can see what i should have could it be the gauge is not working or what

 

Yes, it is very common for our tachometers to grow out of calibration or even quit working altogether. You could borrow another cluster and put it in to find out whether it is the wiring or the cluster.