Brake Lights aren't working, replaced switch, bulbs are good, lights are good.

Well you missed something .Let me ask you this what wasn't working before you replaced the multifunction switch.
The brake lights if the blinkers the running lights the head lights int lights all work must be the contact point or switch at the brake padal or a ground issue to the bulbs or the bulbs are incorrect Ford has this issue with the bulbs they look the same but there not check that for the brake lights .
I have had the same problem the lights work they done work correctly and its hard to tell .Make sure they are the correct bulbs

use a continuity tester to check the wiring from the switch to the brake lights

Go to your brake pedal and see if your brake switch is working properly,push it in with hand and see if switch engages and releases when you let up on pedal.It is adjustable.Also check your bulbs to see if the bulb holder is corruded.Check wiring around bulb too.

Aren't your brake lights and turn signal lights on the same bulb, same filament? Recheck the bulb in the rear, as the rapid blinking is an indication of a burnt out bulb. If the bulb is the correct one and is good, check the connector and socket at the housing for a loose or poor connection.

i have a 1995 gmc truck backup lights not working

Have you checked the brake switch under the drivers side of the dash? There are fairly simple to check. One wire should have power all the time. The other wire should have power anytime the brake pedal is depressed. If there is no power out and power in the switch is bad. If there is no power in than there is an issue with the wiring. Let me know if you have any questions and I'll do my best to answer them. Thank you for using FixYa.com!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Its a faulty turn signal switch.Try this,push down and hold brake pedal while pushing on the hazard switch and if the brake lights come on then replace the signal switch.

the turn signal light switch has nothing to do with the brake lights,the problem is most likely the brake light switch which you should find around the area of the brake pedal it may be faulty or has come loose & needs to be adjusted & tightened back up........hope this helps......cheers.

Yes, you need to of course check the voltage coming into and going out of the brake light switch, if 12 Volts are there going out and coming in while pressing on the brake pedal, your brake lights aren't getting a good ground or there is a break in the circuit between that switch & the lights.

On occasion the tail lights will work with a weak ground circuit where the Brake lights won't. Best way to determine this is to just hook up the 12 volt tester to the Brake light hot wire & there at the bulb ground, then in an area away from the bulb that has a good possibility of contact/ground.

Really that's it, if the 12Volts is getting to the bulb but it isn't lighting, if you aren't getting the voltage there and the brake switch is hot on both sides when pressed, the break in voltage will have to be traced from that switch to the tail light to find the problem.

good luck.

The tail lights working would not necessarily mean that the brake light bulbs are good. If they are the type that have a double filament (ie: one filament for the tail light and another filament for the brake light ) the brake light filament could be bad and the tail lights still would work. If they are either single filament type bulbs or double filament type, I would check the bulb, fuses, and contact switch on the brake pedal.