2006 Chevrolet Equinox Brake Lights

There's no such thing as a "Chevrolet" light bulb. GM buys their bulbs from the same suppliers the auto parts stores buy them from. There are different part numbers that can be interchanged. In most applications they will work fine and might be just slightly brighter, but you will never notice that.

If you watch on your car while a helper works the lights, check if the turn signal and the brake light are different bulbs. If they are, that means the turn signal switch is no longer involved with the brake lights as in the past. That greatly simplifies the signal switch and lowers its cost, but it creates a major headache for people adding a trailer wiring harness. Dead brake lights when the center one still works used to be a problem mostly related to broken wires, but today the insane engineers have hung a computer onto everything. I'll have to find a wiring diagram to see if a computer is involved or if you might be able to do some tests yourself.

If your brake light is the same one that lights up for the turn signal, then you're right that the signal switch could be the cause of the problem.

"I don't know how I could tell whether the brake light and turn signal light are the same by looking at them with a helper, since the brake light won't come on"

Actually, I was thinking the same thing just as I clicked "Submit Answer", but by then it was too late. One thing you can look at is the idiot engineers use yellow turn signal lights on the rear of some cars to confuse the rest of us. Brake lights are always red, so if you have yellow rear signal lights, they use separate bulbs for the brake and signal functions.

The next thing is to at the bulbs through the lenses. Most of the bulbs are going to have two filaments. One is always brighter and is for the signal or brake light. The dimmer one is for the tail light. When you have, ... Wait a minute. I had a better idea. I just popped up a wiring diagram and found that your vehicle does indeed have separate bulbs for the two functions. That means the turn signal switch has nothing to do with the brake lights.

Since the center-high mount brake light works, there isn't much left in the circuit to cause problems. The two brake lights have separate ground wires, so if one is broken, the other bulb would still work.

The place to start is to remove one of the brake light bulbs from the socket, then use a test light or voltmeter to test for voltage while a helper pushes the brake pedal. If voltage is found, the next step is to test the ground wire for continuity. You might also return to the shop where the bulb was replaced and ask them to recheck their work.