Taillight wiring diagram

If after checking the bulbs are ok then the fuses could be suspect!

could be a faulty globe too

If you are not getting power from the headlight switch for that circuit, but the other side works, you'll have to trace the wiring. The socket has two wires plus a ground. One wire is for the tail lamp circuit and the other is for brake-turn signal.

Pull out the old bulb and check power and grounds in the socket. If that checks out then replace the bulb. If they dont then get a wiring diagram and backtrack from the taillight assemblly. If you have a blade type bulb like a 3157 then you might have a melted socket. Good luck!

So the taillights work, but they don't get brighter when you push the pedal? What about the third brake light? If this is the case you need a new brake light switch, it is easy to change and is right on the stick that connects the brake pedal to the rest of the car. also I assume you know how to change a bulb and ruled that out.

it looks like this and costs $25

The bulb has 2 filliments in it ,one for the brake light ,the other for the park light,
I imagine the bulb is bad.

The right side tail light and plate light get their power
from from the left side. The first thing to do is change
the bulb, if this fails, use a 12v test light or meter (the
light easier in this case) and check the power wire
from left to right. If you have power from socket to socket, check the ground, if you have good power and ground and a new bulb. Replace the socket.
Hope this helps. Good luck.

This is the only diagram I could find for tail-lamps. The top wires are voltage, the bottom wire is ground. The brown color wire is voltage for tail lamps. The other color wire is turn or stop, depending. The turn and lower brake lites use the same bulb filament, just not at the same time. The lower brake lites are wired through turn signal switch. I don't know if diagram matches what you have? I looked at several, all showed the same thing.

there are a few things that could be happening here. the easiest way i know to figure out exactly what it is involves some test equipment that you may not have, but it need not be expensive. because your high mount brake light works we know that the brake pedal switch is good. if you are certain that the bulbs in your brake lights are good then you need to see what it is they are not getting. they need ground and power, not getting one or the other. there is a splice pack that i can see on the wiring diagram, but it doesn't tell me where it is. the wire to your brake lights (stop lamps according to gm) is light blue according to the diagram, the turn signal lamp wire is dark blue. follow the light blue wire back from the taillight assembly and see if you can find the splice pack. there will be 5 light blue wires at the splice pack. once you find it you are going to need an assistant, or maybe a pretty good sized rock. brakes lights work with ign off, so do it that way, it's safer. get somebody to hold brake pedal down, or put the rock on it. now go to the splice pack and see what happens when you wiggle it or tap on it. if it makes the taillight stop lamps light you found the problem. if it makes no difference then on to the next step. now you need a volt ohm meter. you can get a cheap one, will work fine for what you are doing. they are available at car parts stores, and though i don't usually name brand names will say this time you can get one at harbor freight for less than ten bucks. with brake pedal off, set tester to ohms or continuity, take taillight assembly apart, remove brake light bulb, and test for continuity between a known ground (pretty much any exposed metal you can find on chassis) and bulb socket. the base of the bulb is the ground side, that's the part of the socket you want to test. you want continuity or almost no resistance. if you can't get that result, you have poor ground. if you find good ground, next test. now with brake pedal depressed, test for 12v between center of socket and ground. set the volt ohm meter to dc voltage in probably the 20 volt range, needs to be more that 12, that's what you will find if all is well. if you have good ground and 12 volts then you must have bad bulbs, or improperly installed bulbs. seems really unlikely. if you make it this far you really wanted to fix this yourself. wish i could make it simpler, but that's how i would do it, suppose it takes longer to tell than do. hope that helps

This video will show you how to replace the taillight bulb in your 01-05 Honda Civic.