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Discussion Starter · #1 ·
II hopped on the other day to ride. I noticed the brake light appears to be stuck in the on position, as if I was holding the brake lever. I wasn't. There's play in the hand lever and the foot lever. I swapped out the front brake reservoir for a Brembo radial. I didn't notice any issues after I made the swap. Also, that was done last year. When this started happening, I don't know. You have any insights that I could look into? Thanks, as always!!
 

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Discussion Starter · #6 ·
I unplugged the rear switch and the front switch, separately. The brake light never went out. It seems to me that by disconnecting them one at a time, I should have been able to tell which sensor was the bad one. Is that correct, or not?
 

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1998 TLS; 2001 TLR; 200X TLRSF
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Rick, you are correct.
The fact that the light stays on when the switches are disconnected says that the White/black wire is shorting to 12 volts or some voltage source within the loom. Start with inspecting the tail light assembly first, as that is a likely location. Sometimes the solder contacts on the back of the bulb develop burrs and short across to the other filament.
If that doesn't pan out, inspect the loom for abrasion points and pinch points. In particular, pay attention to the cables coming from the brake light switches since that is where the white/black wire is bundled with a wire that has 12 volts on it.
Of course, keep the wiring diagram handy.(y)
 

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Discussion Starter · #10 ·
Tony, I probed front and rear switches. The front only had 12 volts going to the one wire. The back showed 12 volts at both wires. What does that tell me? If the rear switch is bad, then why would the brake light be on when I completely disconnected the switch?
 

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1998 TLS; 2001 TLR; 200X TLRSF
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It's good that you tested the taillight separately. Now you can remove it from the circuit and concentrate on the loom wires.

Tony, I probed front and rear switches. The front only had 12 volts going to the one wire. The back showed 12 volts at both wires. What does that tell me? If the rear switch is bad, then why would the brake light be on when I completely disconnected the switch?
At this point, if I am understanding your comments correctly, the brake light remains on with both brake switches disconnected. Correct?
If so, then leave it in that condition and remove the 15A Signal fuse (fuse #4). The lights should go off. That tells you the 12v source is coming from the Signal circuit and not the ignition, headlight, or fuel circuits.

Now, if you are still with me, turn the key off and leave the Signal fuse removed.
Connect your ohm meter to the two wires at the rear brake light connector on the loom side; that is the Org/green and White/blk wires at that connector.
Since a short exists in that section of the circuit, the meter should show a very low resistance between those two wires. What value do you see?
Now, while monitoring the meter, disconnect the Large White Gang connector between the two looms. Does the meter still show a low resistance? If so, then you know the problem is in the rear section of the loom.
Now, it is just a matter of following the White/blk wire through the loom to see where it is shorting to the other wire. Look for pinch points.

I know it sounds involved, but it is really not very complicated. The most difficult part is gaining access to the loom. That's why you'll want to look at the more obvious and accessible pinch points first.
 
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