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Post by poborne on Sept 1, 2020 20:02:34 GMT -5
Hello All,
So as I'm learning about my new-to-me GT, I found my brake lights don't work when pushing the brake pedal. They work as 4 way flashers, turn signals, and when I turn the lights on, but not when I press the pedal. Any ideas on what to check?
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Post by jspbtown on Sept 1, 2020 20:21:06 GMT -5
Yup...the brake light switch(s) at the master cylinder.
They might be unplugged or they might be broken.
Take the wires off...jump them together...if you get brake lights you have a bad switch (or two). If the brake lights don't work when you jump the wires you have bad wiring and who knows where that might be on an old, home built car
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Post by poborne on Sept 2, 2020 7:56:37 GMT -5
Thanks for the advice! I will check this and see what I find. The car is built really well, so I'm pretty hopeful that it isn't a wiring issue.
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Post by jspbtown on Sept 2, 2020 8:12:51 GMT -5
Depending on what master cylinder you have you will either have 1 or 2 brake light switches. The factory set up uses two switches which incorporates a brake warning light. If your Bradley doesn't have that light then you can just use 1 switch and have the other one attached, but use it as a "spare" since these often fail.
The switch is simply a pressure switch. Power comes in one contact and when the brake it depressed the switch allows the power to pass through to the other contact. So...and this is of course dependent on how your individual car was wired....you should have 1 wire coming in, maybe some wires going from switch to switch, and then 1 wire leaving. If that the case (and you have jumped the wires to make sure its not a wiring issue) then you can take the the wire coming in and the wire coming out and just hook them up to one switch.
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Post by poborne on Sept 2, 2020 15:46:57 GMT -5
Ok so I've confirmed that mine has 2 switches, there are two wires connecting to one of them. I took them off and touched them together and got nothing. So I started the car and did the same, nothing. I then hooked them up to the other switch and pressed the brake, nothing. Started the car and pressed the brake, nothing. Turned the lights on and tried, nothing. I do have an emergency brake light on the dash. So where do I go about testing it from there?
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Post by jspbtown on Sept 2, 2020 17:28:14 GMT -5
OK...so I assume you have the stock Bradley tail light set up? Generally speaking the top (or sometimes the bottom) two are the turn signals and the parking lights. The bottom two are generally the brake lights and parking lights.
So when you have your headlights on all 4 lams should be on dimly. When you put the brakes on the bottom two should come on bright. When you put your flashers on the top two should flash brightly.
Can you be a little more specif as to what each lamp is doing and when?
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Post by poborne on Sept 2, 2020 18:17:37 GMT -5
It is the stock tail light setup. When I turn on the lights all 4 light up dim. When I use the turn signals, the top ones blink. When I turn on the flashers, the top ones also blink. The bottom stays dim for turn signals and flashers. When the brake pedal is pressed, nothing. I can't get the e-brake light in the dash to come on when I pull the e-brake either.
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Post by jspbtown on Sept 3, 2020 7:21:23 GMT -5
Are the two lower brake light filaments burnt out?
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Post by poborne on Sept 3, 2020 7:47:10 GMT -5
I thought about that, and pulled the left lower side to check. The filaments look good. From looking at the schematic there doesn't seem to be much to the brake lights, so I'm puzzled why they don't work especially when all the other lights are fine. I thought maybe the two switches need to be wired for it to work (wire coming in to one, from that one to the next switch, then wire coming out) but that wouldn't explain why they don't work when I touch the two wires together. Could the e-brake light not working give any clues to it?
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Post by jspbtown on Sept 3, 2020 9:00:15 GMT -5
Well one of the wires at the switch should have keyed power to it. Did you try a test light to see if you had power there? Have you checked fuses?
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Post by poborne on Sept 3, 2020 9:13:02 GMT -5
I need to purchase a test light. I did take a look at the fuses, and they look good. I have a multimeter, so I can use that to check the voltages. I'm not sure if I have a 6 volt or 12 volt system, or if I have an alternator or generator (If I remember right, generators are only 6 volt and alternators are 12 volt). If it is a generator, I'd like to switch it to an alternator but I wonder about the other changes I may need to make to accommodate it. I also thought about trying to clean up the connections at the brake switch to see if it improved the contact. I did find the dual brake switch schematic in the manual, and plan to check the wiring in regards to that with the e-brake light. The schematic shows 3 prong brake switches wired together and a wire coming from them to the e-brake light for it to work. Could that possibly be why they aren't working?
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Post by jspbtown on Sept 3, 2020 10:33:47 GMT -5
The battery will tell you what system you have...put your multi meter on it.
If you have a 12 volt generator than they sell kits to swap out to an alternator. You need a new stand and a new backing plate for the fan shroud.
IF you have power at one wire (key on) and no brake lights when you jump the wires its a wiring issue or burnt out bulbs. The switches are just pressure switches. They make contact when they have brake line pressure and then lose contact when the pressure is released. Its an amazingly simple system, but they are subject to failing.
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Post by poborne on Sept 3, 2020 17:00:53 GMT -5
Ok so I bought a tester. I tested the wires at the switch, nothing. I tested a wire I knew was hot to verify my ground and it was fine. So I got under the dash and started testing the fuse block. I found that fuse 1 was hot on one side and not the other. It looked good, but I pulled it anyway and put a new one in. Voila! I have brake lights! Thank you for the help troubleshooting!
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Post by jspbtown on Sept 3, 2020 18:45:33 GMT -5
Excellent....the best solutions are always the easiest solutions
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