No brake lights?

Good evening,

I attached a wiring diagram below for you to view.

There is a fuse for the brake light switch. Check for power there and at the switch. They are in the diagrams I attached. Make sure there is power on both sides.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

The power goes to the stop light switch and then off to the body control module. The switch sends a signal to the body control module and the module sends voltage to the brake lights, all of them.

You need to start with checking the fuses and check for power at the stop light switch both in and out.

https://www.2carpros.com/articles/how-to-check-wiring

Roy

Is the truck wired for towing? If so often this added wiring will chafe and go to ground. So check this out.
If no hitch wiring check the bulbs they can short and cause the problem.
Good luck

Wouldn't surprize me if the sockets were bad.

Yup, we went through so many of them at the dealer I was at we couldnt keep them in stock

Next step is to check the wiring going back to the brake lights also check the connectors to see if any are unplugged see if anything else is not working to as this could be an indication of a wiring connector coming unplugged

Hi and thanks for using 2CarPros.

The first thing I suspect is a bad ground. Both tail lights have a common ground. However, the third brake light has a different one.

What I suggest is this. First, remove the light assembly and locate the wiring to the brake light bulb. Have a helper press the brakes while you check for power to the yellow wire on the left light assembly and dark green one on the right side assembly. Make sure you have a good ground for the test light. If it turns on when the brake is applied, then you have a bad ground.

I attached a picture for you to see the brake lights and their ground. It indicates where the ground is located and the color of the wires.

Here are a few links you may find helpful when performing the test:

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know if this helps or if you have other questions. And, I hate to ask this, but are you certain the bulbs are good and the correct ones?

Let me know.

Joe

Your lower brake lites are wired through the turn signal switch. At the lower rear, brake and turn use same bulb filament, just not at the same time. The white wire carries voltage to turn switch for lower brake lites. The high-mount brake lite is not wired through the turn switch. The brake lite feed from turn switch, dark green for right side, yellow for the left.

The relay you replaced, is it the brake switch at the brake pedal or another one under the hood somewhere?

It sounds like you are describing a failed brake pedal switch. Also, the third brake light is on a separate circuit than your rear brake lamps so will not be a symptom.
One follow up question, do either of your turn signals work properly? Try them with the headlamps turned on and off and we'll see what we can do.

Regards.

That's great news! You have a simple fix of replacing your brake pedal switch located on the lever part of your pedal. It is easy to install, practically just pops out and in, and can be found at any parts store.

Make sure it is adjusted properly once you put it in. With the brake pedal at rest (not depressed) move the switch towards the pedal until the plunger is fully depressed.

Regards.

Hi, your lower brake lites and turn signals, use the same bulb filament at the rear, just not at the same time. They are wired through the multifunction/turn switch. You can go ahead and check voltage and ground at the rear. Ground wire is black, it may be a dual filament bulb, the other filament is tail lamp, brown wire, the other color wire has to be turn/brake. The high mount brake lite, where applicable, is wired differently.

Use a voltage tester on the proper wire in the diagram. At the rear, brown wire is voltage for tail lamps, The other color wires are voltage for brake/turn. The info I looked at was for c1500.

Check the black wire in the diagram for proper ground.