The most likely causes of a brake light staying on are:
* Low Brake Fluid: This is the most common cause. Check your brake fluid reservoir (usually a clear plastic container near the master cylinder under the hood). If it's low, you have a leak somewhere in your brake system – a serious problem requiring immediate attention. Do not drive the car until this is fixed. Adding fluid is only a temporary measure; you need to find and fix the leak.
* Faulty Brake Light Switch: This switch is activated by the brake pedal and turns the lights on. It can wear out or become misadjusted. It's usually located on the brake pedal assembly itself. You may need to replace it.
* Burnt-out Brake Light Bulb(s): While a burnt-out bulb *wouldn't* keep the light constantly on, a short circuit in the bulb socket could. Check all your brake lights (including the center high-mounted stop lamp if equipped).
* Wiring Problem: A short circuit or damaged wiring in the brake light circuit can cause the lights to stay on. This requires tracing the wiring to find the problem.
In short: You don't reset it. You *diagnose and repair the underlying problem* causing the brake light to stay illuminated. Because brake failure is a serious safety hazard, if you're not comfortable working on brakes yourself, take your Fairmont to a qualified mechanic immediately.
