I'm having a hard time figuring out what is wrong with my brake lights. Both turn signals work properly. What I have tried checking fuses. What else can I try?

 

Welcome to the forum

1990 Ranger?

The brake and turn wiring changes over the years in Rangers so YEAR is important
1999 and earlier use separate bulbs for turn and brake
2000 and up share brake and turn in rear bulbs

Does the 3rd brake light on the cab work?

If 3rd brake light doesn't work then brake switch on the brake pedal make be broken, or fuse is blown

And any time you have any rear light issues always have a look under rear drivers side of truck, you are looking for "trailer wiring", there are many DIY trailer hook ups done over the life of any pickup truck, some of its done well, some............not so well, lol
And it gets ALOT of water and dirt on it, so can corrode over time

 

For the trailer wiring it is there should I just replace it with a new one? You seem to have way more knowledge about rangers then myself but it looks like there is only room for one bulb in the brake light housing not enough room for a turn bulb and a brake bulb? Thanks for all your help so far.

 

What YEAR RANGER????

 

It's a 1999. 2x2. With a small backset flex fuel option. Side flare.

 

Fuse #13 20amp in cab fuse box
swap it out with another 20amp fuse or test it with ohm meter, "looks OK" means chase your tail for next day or so, lol.

If 3rd brake light on the top back of cab works then fuse and brake pedal switch are OK
Brake light switch has power all the time, not a key on circuit
So get a long stick stand outside so you can see the 3rd brake light and push down brake pedal with the stick to see if it works, if not then fuse or switch problem

1999 uses separate bulbs in the rear for brake/park, turn and reverse, turn are usually at the top and yellow, reverse is lower and white
Brake/park is a DUAL filament bulb, so 2 separate lights in one glass bulb

1999 tail lens seen here:
They are easy to pull out to test or change bulbs, just 2 screws

The Light Green wire(no stripe) is the brake light wire that runs from the brake pedal switch back to the rear of truck, it splits on drivers side rear under the bed with 1 Light Green wire going to drivers side brake light and another Light Green wire running over to passenger side brake light

Trailer wiring needs to Splice into this wire to get brake lights on the trailer, if done poorly it can, over time, CUT the wire at the splice point, this wouldn't effect the 3rd brake light on the cab, just the rear brake lights
The popular splice connector for DIY looks like this: https://www.curtmfg.com/part/58280

If you see these under rear drivers side then they can be the problem, not the first thing to check but as you run out of other things then have to test the one on the Light Green Wire