God damn wiring - Honda RC51 Forum : RC51 Motorcycle Forums
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post #1 of 10 (permalink) Old 11-13-2013, 04:39 PM Thread Starter
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God damn wiring

here's the part of mechanical maintenance/work I hate. wiring, especially in the tail section. cos as usual, this is something the PO did himself when fitting the modified undertail lights, so its a mess.

when the electrics are on and the lights are fitted, both my rear lights stay on the highest brightness (brake lights stay on) when both lights rear are connected up.

but then next time, only one light works and the other just flickers.

i have my suspicions, but i took a pic of the wiring to show you guys to see if anything bad stands out.
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post #2 of 10 (permalink) Old 11-13-2013, 05:21 PM
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Looks about like mine

If mine wasn't working properly, like yours isn't, I'd take it all apart and start over.

Actually, I'd take it apart 1 by 1, checking things with a multimeter and labeling them as to what I found (voltage, blinking, etc)
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post #3 of 10 (permalink) Old 11-13-2013, 06:05 PM
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By the looks of it, some of the problems may be poor crimp connections.
If there's an electronics store nearby, I'd take a trip to find better quality crimps, connectors, and crimping tools.

As a side note, this is what greeted my eyes when I opened my trunk after I bought it.
So don't feel too bad. I had to replace all my wiring harnesses to set things right.

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post #4 of 10 (permalink) Old 11-13-2013, 06:58 PM
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dang, i wouldve shamed the PO if thats what i saw when i was tryin to buy the bike.. makes u wanna check all electrical front-back to make sure he didnt hack up anymore wiring..

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post #5 of 10 (permalink) Old 11-13-2013, 08:34 PM
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That's nuthin SubSailor, nuthin I tell ya ... PO of mine ran all the rear lighting wires OVER the tail cross support tube that supports the passenger ... and the wires were so short that he couldn't even route them to the ends (sides) of the tube ... so they sat directly under the two plastic rear seat support feet and his fat wife's ass smashed all the wires flat as a flitter. Very surprised no short circuits.

Oh, and he was fat, too. And Sweaty.

Nice people, though.

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post #6 of 10 (permalink) Old 11-13-2013, 08:40 PM
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Wiring really isn't all that difficult.

First you need to think about where you're going to locate loose items. Route the wires and make sure you get the best "permanent" locations for things. You don't want to be re-arranging wiring after you've done a good job of putting on new connectors. Zip ties are a life-saver here if here are no tabs. Make sure the components are well out of the way of luggage, tool kit, etc. under the seat cover.

Get a simple 12v test light. I bought one of these from Ebay recently and it's a good one - better than most. Bad thing is you have to wait for it to arrive from China, but this is a tool any DIY person should have in his box.


You connect one end to the frame, or something negative earth and poke a wire with the sharp end to check for live (Or better still - at the electrical terminal if there's access). If it comes on when you pull your brake lever, you've found the wire for your brake light +ve.
If it stays on, it's your tail lights (Check the switches and see what happens). If it flashes it's a winker.

If nothing makes it live, then it may be 've earth...

Couldn't be more simple to test electrical circuits with one of these. A multimeter is more cumbersome to use for checking simple continuity. Where you think you may have a broken wire, poke the tester along it's length. If there is a break in the wire, it'll work on one section and not the other. Then you've found your fault.

Get some proper crimping pliers for brass / aluminium terminals / spade connectors (male & female) (Go to a good electrical or car parts shop, they should sell these - Halfords is not the place!) or buy from Ebay if you're a lazy shopper like me.


Get yourself some box connectors too. Say if you have 3 wires going to the brake lights, get a 3-way connector box. 2 way terminals for indicators.

Here's a few quickly searched examples of what I'm on about - available from Ebay.




You can also get a soldering iron and solder. Basically where you want to join two wires you'll be twisting wires together in a continuous line - and applying heat (A larger soldering iron is better than an underpowered one!) to the wire - and the solder will melt if in contact with the joint at the same time. It also helps to "tin" the end of the soldering iron. Check on Youtube how to solder. It's easy-peasy.

Whilst you're buying a soldering iron - buy some shrink wrap, which is a thin plastic tube that will shrink when you pass a lighter or soldering iron underneath to heat it up (Don't burn through it though).

There should never be wires wrapped around one another and held together by insulating tape. That's asking for trouble...

Do the job methodically and tidily. Take your time and THINK / Double check you have everything right (Shrink fit over the wires first & through the box before crimping or soldering!). You might want to practice with the crimping tool first, to make sure you know how to crimp copper / aluminium terminals. If you make a mistake, have spares terminal boxes just in case. These types of connectors are not expensive things to buy.

Hopefully the above will help you get your wiring sorted under there. It's not good to have brake lights on permanently!

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post #7 of 10 (permalink) Old 11-14-2013, 10:34 AM
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From the sounds of things, you have the running light wire (bike side) hooked up to the brake light wire (light bulb side)

Stig hit the nail on the head. Electrical work like this isn't rocket science. Just take your time and plan it out.

I'm always right.

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post #8 of 10 (permalink) Old 11-14-2013, 11:59 AM Thread Starter
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I bought some 3 way connectors earlier today from fleabay. will try them out.

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post #9 of 10 (permalink) Old 11-14-2013, 05:53 PM
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huhhuh you said 3-way

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post #10 of 10 (permalink) Old 11-14-2013, 07:42 PM
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Originally Posted by LDH® View Post
huhhuh you said 3-way


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