2000 RC51 rear break light issue | GTAMotorcycle.com

2000 RC51 rear break light issue

KyokushinFighter

KyokushinFighter

Well-known member
2000 RC51 rear brake light issue

Ok, my rear brake won't make the light come on. The front works fine. The small sensor that sits on the rear set has had the wires cut by one of the previous owners between the sensor and the plug. It worked fine until last season. I took the tape off and touched the bare wires (no solder or shrink wrap) and didn't get shocked or see any sparks etc. Maybe no power getting to the sensor? I am no good with electrical stuff. HELP!
Thanks.
 
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check continuity at the sensor when its pulled/not pulled.

its a simple device....if wires are cut, twist them (solder+shrink wrap) and tape and off you go
 
The wires were only twisted and taped, could they have gotten wet and shorted out? I don't have any electrical testing equipment like a multimeter or light tester. I pushed the brake pedal down with my fingers on the wires and got no shock. That is the extent of my electrical testing abilities! lol
 
blown fuse....check those first...
 
Ya I should probably check that first before I start getting too worried about it.
Thanks
 
Ok, the fuse is good. The running light also works. Just the rear brake issue. I hate electronics ! lol
 
Try adjusting the switch on the rear brake lever. It will have a black plastic lock nut that you loosen, then turn the switch in or out until the light works when pushing lever. Re-tighten the lock nut when complete. Good luck.
 
rocketrc51 said:
Try adjusting the switch on the rear brake lever. It will have a black plastic lock nut that you loosen, then turn the switch in or out until the light works when pushing lever. Re-tighten the lock nut when complete. Good luck.
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Nothing wit this suggestion either. I don't have any black plastic lock nuts on anything in that area. But I am sure I was adjusting the right nut. Dead switch maybe?
 
Thanks Rocket, I will give that a mess with tomorrow when I get home. I loosened that nut before and a small amount of brake fluid came out. So I tightened it back up. No air seems to be in the lines. I HOPE! lol
 
KyokushinFighter said:
Thanks Rocket, I will give that a mess with tomorrow when I get home. I loosened that nut before and a small amount of brake fluid came out. So I tightened it back up. No air seems to be in the lines. I HOPE! lol
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You should NOT have had any fluid come out. This is a switch that has NO oil. Check out page 461 or section 19-20
 
Well there was a small bit of brake fluid looking substance at the bottom of that nut. Under the switch and nut there is the brake line. It is one of those lines with the open ring ends. The best way to describe it would be a magnafying glass shape with the hose running to the rear brake. I will have a closer look tonight.
 
ok guys,

Here is a pic of my rear brakes. Note the empty mounting tab next to the frame. That is where the brake light switch SHOULD be. Also note the small red electrical device on top of the master cylinder. That should NOT be there. This bike has been dropped by the very first owner on that side. I have looked at dozens of RC51 pics of all years and this red device does not show up on anything I can find. It is the only electrical bits on the rear brake. It did work when I got it safetied. It was tested right in front of me. I don't think there is a rear brake light switch thief around! lol
What do ya think?
-Matt
 

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Oooooohhh ... That is not the original-equipment setup. What you have there is a pressure-activated switch. That's fine, it just isn't original equipment.

Pressure-activated switches are not adjustable. They either work, or they don't. I suspect that in your case, the switch is probably fine, but someone did a butcher-job of wiring it. You don't just twist wires together and tape them ... you SOLDER wires together (and you have a section of heat-shrink insulating tubing over one of the wires, away from the soldering area, already prepared when you do this), then shrink the insulating tubing over the solder joint, then check for proper function, then tape the harness.

Anyway, the harness to the switch should have two wires in it. One of them is power, the other goes to the brake lamp. Untape all that mess and touch the two wires from the harness together with the ignition key on. Does the brake lamp come on? If so, then the underlying circuit is okay.

If it passed that test, then use a multimeter to measure the resistance between the two terminals on top of that switch. It should read infinite resistance when you are not activating the brake, and almost zero (less than 1 ohm) when the brake is activated. If that is what happens, then the switch is working.

If you have gotten to this point then the fault lies with the crappy electrical connections. Re-do them *properly* and your problem is solved.
 
KyokushinFighter said:
ok guys,

Here is a pic of my rear brakes. Note the empty mounting tab next to the frame. That is where the brake light switch SHOULD be. Also note the small red electrical device on top of the master cylinder. That should NOT be there. This bike has been dropped by the very first owner on that side. I have looked at dozens of RC51 pics of all years and this red device does not show up on anything I can find. It is the only electrical bits on the rear brake. It did work when I got it safetied. It was tested right in front of me. I don't think there is a rear brake light switch thief around! lol
What do ya think?
-Matt
Click to expand...


I would pick up a stock replacement that fits in the hole of the bracket directly in front of the red unit and connect the wires to the new stock unit.
 
I am thinking the same thing. The wires to that red piece are the ones that were cut and taped. I am assuming that this is what is causing my headaches. I wonder what Honda will charge for that part! lol I am going to call the dealer on tuesday just to get a laugh.
 
So someone's replaced your pedal operated switch with a hydraulic pressure switch. That is not unheard of, but is usually done in custom situations, such as adding a brake light to a bike that didn't have one, or moving the pedal. It makes the connection to turn on your brake switch when hydraulic pressure from the application of the brake pushes on the diaphragm/plunger. they can be tested for operation like any other switch, with a voltage or continuity tester. They are available at any place that sells hydraulics, maybe at some auto parts shops.

Edit: took too long to type that one, I see I was beaten to the punch.
 
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Thanks for all the help guys. I will get some prices and do some more of my patented shock therapy voltage testing! lol
 
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