Tech Tip- Brake Light Switch

BRAKE LIGHT SWITCH

Do your brake lights on your 55-57 Thunderbird work only sometimes, only if you press hard on the brake pedal, or not at all? The problem may be your brake light switch. If they work sometimes or only if you press hard on the brake pedal, the problem is most likely this switch. The brake light switch is located in the engine compartment on the frame under the steering column near the inner drivers side fender well. Follow the brake line until you see the line go into a round, metal housing with two wires coming out of the center on the top side. This is your brake light switch. To replace, simply disconnect the wires from the switch and unscrew the switch from the brake line. Do not press on the brakes as this will cause brake fluid to flow from the opening in the brake line at the switch location. Replace the old brake light switch with the new part immediately to prevent any air from entering your brake lines. Don't forget to reconnect the wires. To be on the safe side, you should bleed the brake lines to purge any air from the system. If your brake lights did not work at all before you replaced the brake light switch and they still do not work, you may have a short in your electrical lines from the switch to your rear lights and the problem is probably not your brake light switch. The brake light switch itself is available from most local auto parts stores and is relatively inexpensive. This switch is hydraulic and is activated by the brake fluid when pressure is applied during braking. This switch has a tendency to grow less sensitive with age. The same switch was used on all Thunderbirds from 1957 to 1964 and on Ford Pickup Trucks from 1957 to 1967.

source: CTCC Tech-Tip Manual 1993-1997