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Discussion Starter #1
I have an 05 FXST running lights work fine in the rear but my brake light doesn't light up at all whether I hit front or rear brakes I just replaced the bulb because I had nothing but now only running lights anyone have any ideas?
 

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The brake light circuit is fairly simple. It is either the bulb, the wiring or the switches.

The easiest things first. Check all of your fuses.

I guess it is possible that both switches are bad. You can check the rear switch by unplugging the wiring from the switch and jumping the two wires together. Trace the brake line back from the rear master cylinder, and you'll find the switch. It is a small plug with two wires plugged to it. Pull the two wires and jump them together to see if the brake light lights. If so, the switch is bad.

It's a little tougher to jump the front switch, but it can be done. You can either trace the complete right-side wiring down to where it plugs in at the steering head and unplug it there. (You'll need to know the right ports in the plug to jump.) Or, disassemble the switch cover test it right at the switch.

If that gets you nowhere, you need a meter or test lamp to test voltage. Test the voltage at the bulb socket with a meter. If there is no voltage there, test it again where the tail light plugs in to the rear lighting harness. If you get voltage at that socket, the tail light housing has a broken connection in it somewhere.

If you still have no voltage, take the seat off and check the plug under the seat that couples the complete rear lighting assembly to the main harness. If you have voltage on the main harness side of that plug, you know which side to start tracing wires.

You can wrap a strap or whatever you have around the front lever to hold the brake on.
 

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So, lessons learned: Number one, it's always the simple stuff, let me start off by saying that the malfunction is now corrected, I used your suggestion and jumped the rear switch and that actually led me to discover the actual problem because the light did not work but I did get some crazy readings on the multi meter which led me to check the entire wiring harness from the light all the way to the fuse box. Number two, having your neighbors there to help you works a whole lot better than talking to yourself and swearing at your bike! Finally number three, a bad ground which is what it ended up being will cause all sorts of havoc on your bike and make you think you are crazy. Make sure you check the grounding bar on the frame of your bike right under your seat for corrosion this will cause anything to malfunction in my case just the break lights. Multi meter works great for this because you can switch it to ohms and check the circuit and the ground. Thanks for your help.
 

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So, lessons learned: Number one, it's always the simple stuff, let me start off by saying that the malfunction is now corrected, I used your suggestion and jumped the rear switch and that actually led me to discover the actual problem because the light did not work but I did get some crazy readings on the multi meter which led me to check the entire wiring harness from the light all the way to the fuse box. Number two, having your neighbors there to help you works a whole lot better than talking to yourself and swearing at your bike! Finally number three, a bad ground which is what it ended up being will cause all sorts of havoc on your bike and make you think you are crazy. Make sure you check the grounding bar on the frame of your bike right under your seat for corrosion this will cause anything to malfunction in my case just the break lights. Multi meter works great for this because you can switch it to ohms and check the circuit and the ground. Thanks for your help
 
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