1957 Brake Lights Inoperable

[57DukeofAle]

I am trying to figure out what the problem could be before I crawl under the dash. I checked for continuity on the hydraulic brake light switch and have continuity when I step on the brakes. The turn signals work properly. All the light bulbs work. I believe the turn signal and brake light is the same filamet. I checked for voltage on each of the two green wires that attach to the brake light switch and there in no voltage on either one. The cigar lighter works as does the radio. It is hard for me to get down and look behind the dash so I woul like to have an idea of wht color wires to check without looking at everything. Any ideas would be greatly appreciated.

Thank you, Dukie

 

[Ward 57]

I am trying to figure out what the problem could be before I crawl under the dash. I checked for continuity on the hydraulic brake light switch and have continuity when I step on the brakes. The turn signals work properly. All the light bulbs work. I believe the turn signal and brake light is the same filamet. I checked for voltage on each of the two green wires that attach to the brake light switch and there in no voltage on either one. The cigar lighter works as does the radio. It is hard for me to get down and look behind the dash so I woul like to have an idea of wht color wires to check without looking at everything. Any ideas would be greatly appreciated.

Thank you, Dukie

According to the wiring diagram in the electrical manual There is a green wire from the back of the light switch at terminal 'A' going to the switch and should be constant hot.
It sounds like you know how to use an Ohm meter and have verified the switch works. I don't see anything else on the circuit before it goes to the turn signal switch. I think the place to look is the light switch and make sure that connection is intact & clean.
Your tracking down the issue is half the fun and your assumptions on the bulb filaments are correct.

 

[doug7740]

I am trying to figure out what the problem could be before I crawl under the dash. I checked for continuity on the hydraulic brake light switch and have continuity when I step on the brakes. The turn signals work properly. All the light bulbs work. I believe the turn signal and brake light is the same filamet. I checked for voltage on each of the two green wires that attach to the brake light switch and there in no voltage on either one. The cigar lighter works as does the radio. It is hard for me to get down and look behind the dash so I woul like to have an idea of wht color wires to check without looking at everything. Any ideas would be greatly appreciated.

Thank you, Dukie

Dukie,

Since you stated that there is no voltage on either of the green wires at the stop lamp switch, you need to check where the green wire connects to terminal "A" of the headlamp switch. If the connection is clean and tight, then check for voltage at terminal "A". If you do not have any voltage at terminal "A", then the internal connection from terminal "B" inside the headlamp switch is open. Since voltage to the clock also comes from terminal "A" of the headlamp switch, if the internal connection was open, the clock would also be inoperable.

doug7740
1955 Thunderbird Blue

 

[57DukeofAle]

Dukie,

Since you stated that there is no voltage on either of the green wires at the stop lamp switch, you need to check where the green wire connects to terminal "A" of the headlamp switch. If the connection is clean and tight, then check for voltage at terminal "A". If you do not have any voltage at terminal "A", then the internal connection from terminal "B" inside the headlamp switch is open. Since voltage to the clock also comes from terminal "A" of the headlamp switch, if the internal connection was open, the clock would also be inoperable.

doug7740
1955 Thunderbird Blue


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Thank you very much. That is the info I was looking for. And also the clock does not work.

 

[Ward 57]

Thank you very much. That is the info I was looking for. And also the clock does not work.

It should be easy to see if there is power to the clock. My clock would work occasionally so I took it out to clean and oil. The '57 clocks are unique to the T-birds Made by Borg, all the other cars had westclock clocks.
The clock has several layers and all the bushings between the layers were deteriated and the movements were binding. I had the option to have it rebuilt or converted to quartz. I had it converted and let the shop keep the old parts in case someone needed a concours correct clock.

 

[57DukeofAle]

I would like to report that I have finally solved the problem with my brake lights. Thanks to those that posted the diagrams and help I discovered that the wires connected to post A and D on the headlight switch were reversed. I repositioned them and the brake lights now work. So much for assuming that the wiring is correct after 66 years! Thank you all.

Dukie

 

[swatson999]

I would like to report that I have finally solved the problem with my brake lights. Thanks to those that posted the diagrams and help I discovered that the wires connected to post A and D on the headlight switch were reversed. I repositioned them and the brake lights now work. So much for assuming that the wiring is correct after 66 years! Thank you all.

Dukie

What post "D" are you referring to?

 

[57DukeofAle]

What post "D" are you referring to?

Post A and D on the headlight switch. Post D has 2 wires Green with Yellow tracer and are for the left and right door jamb switches

 

[swatson999]

Post A and D on the headlight switch. Post D has 2 wires Green with Yellow tracer and are for the left and right door jamb switches

OK, thanks. I see it now...it's not labelled on the diagrams, but I see the D marking on the pic of the switch body.