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1. A blown fuse. The first thing you should check is the fuse that controls the brake lights. If it's blown, replace it with a new fuse of the same amperage.
2. A faulty brake switch. The brake switch is what tells the brake light to come on when you press the brake pedal. If the switch is faulty, it won't be able to send the signal to the light, and it won't come on.
3. A bad ground connection. The brake lights need to have a good ground connection in order to work properly. If the ground connection is bad, the lights won't be able to get the power they need to come on.
4. Damaged wiring. The wiring that connects the brake lights to the brake switch and the power source can become damaged over time. If the wiring is damaged, the lights won't be able to get the power they need to come on.
*Here are some additional things you can check:
* Make sure that the brake light bulbs are not burned out.
* Make sure that the brake light sockets are not corroded.
* Make sure that the brake light lenses are not cracked or damaged.
* If the brake lights still do not work after checking all of these things, you should take your Toyota 4Runner to a qualified mechanic for further diagnosis.
*Remember the following Safety precaution:*
To avoid an accident do not drive if your brake lights are not functioning properly. If you're going to drive the car at night before fixing the problem, make sure to let other drivers know that your brake lights are out by using hand signals or by putting a piece of paper in the rear window that says "Brake Lights Out".
