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Good morning everyone, last week I picked up a 1949 F1 in decent condition. About 98% restored, but a few minor problems. One problem I am having is to get the brake lights to work. Tail lights work fine, but no power to the brake lights. I changed the switch on the master cylinder and still nothing. There is power going to one terminal on the switch but nothing on the other side. If I jump across the switch the brake lights will come on. Any ideas or help with this issue would be appreciated. Thank you in advance
This points to the switch. What new switch did you get? What is the activation pressure? Are you able to build and meet that pressure? Swapping the switch can lead to air in the lines which can mess things up. Also, there is a tendency to go gorilla tight on the switch and this can distort it preventing it from working.
The part numbers may vary depending upon your exact year and model truck.
There will be those who curse the original style pressure switch setup and will praise all sorts of mechanical hacks, but that isn't how things should be done IMHO. They could be masking a real issue of fluid contamination, too much residual pressure, insufficiency bled brakes, bad grounds, improper installation and so on...
Thank you for your input. The only place in my area where I could get a switch was Napa. I will take it back out make sure everything is good and clean then replace it
Or for more money, Harley Davidson used to sell a low pressure version that fits the Ford truck master cylinder. (1/8" pipe thread iirc)
20+ years ago the pn was 72023-51D Brake light switch kit, rear. It solved my problems and has been compatible with Dot 3.