Electrical Fault Finding

johnnysneds

Senior Member
Joined
May 14, 2011
Location
Chiang Mai
Bikes
Multistrada 1200S Touring, WR450F, KTM200EXC, Gas Gas 280, PCX
Over the past few months Ive been on rides with guys who have had electrical problems with their bikes. So I thought I would start a thread of where to begin first in your quest to get her going again and hopefully you wont be chasing your tail for days.

Ill also be using material I have found from several sources in the past that I have found of great benefit.

Firstly lets start with the charging system

Any well-working modern motorcycle charging system will produce a voltage over the battery terminals in between 13.5V DC and 14.5V DC, over the entire rev range. When you suspect a fault in the system, this is the first thing to check on your bike.

When you find that there is a problem, keep in mind that the number 1 problem with any charging system are bad connections.

Suspect any connection in the entire system. It's advisable to take off all fairing parts, the fuel tank and seat, and just disconnect all connectors you can find. Do these one at a time, and spray them with a contact cleaner before fitting the connector again. On the widely used bullet connectors, the ones used on many Japanese bikes for connecting single wires to each other, you should see if the male bullet connector needs a firm push when it slides into the female one. If not, use a pair of pliers to make the fit tighter in the female connector.

When you disconnect them one at a time, nothing can go wrong. You will see that the wires are color coded, so mistakes when refitting the connectors are almost impossible, almost!

Click this link to download a flow diagram fault finding guide to assist you with your charging system diagnosis: https://files.me.com/sned111/l1d0qh

Click this link to download an excellent guide to testing the diodes withing the regulator part of your Regulator/Rectifier (R/R): https://files.me.com/sned111/ar4php

Now the main tool to be used is a digital multi-meter. It doesn't have to be a fancy one, these are readily available in shops like homeworks etc for a reasonable price. Mines was 500 Baht or something. The smaller the better and the more practical to take on trips with you.

Now before you get stuck in and rip your electrical charging system apart I would advise spending some time to learn the basic principles first. The more you understand the theories the quicker you will use the meter when fault finding.

Have a read of this article "How a Motorcycle charging system works" http://www.electrosport.com/technical-r ... stem-works
Its very good and kinda keeps things simple. Anything confusing I can try and explain it a bit better.

In a nutshell we have a "Stator" which produced 3 Phase A/C by electro magnetism when the engine rotates. A/C is no good to most motorcycle electrical systems, although there are bikes which run on A/C without a battery at all, so we need to convert it to D/C, this is where the "Rectifier" comes in. We dont want the battery to get supplied all the time so we need something which will keep an eye on the voltage being supplied to the system/battery and regulate it as necessary this is called the "Regulator" and is part of the R/R unit.

Before I end this first parts I should mention safety as it is electricity after all. Note that it only takes 40 odd milliamps to stop your heart. To put this into perspective my radiator fan draws just over 2 amps.
If your not 100% sure what your doing, don't do it and ask. You'll either end up damaging your system or worse hurting yourself.
 
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