Electrical Troubleshooting

Troubleshooting an electrical problem on a motorcycle is normally relatively simple and cheap. 
 One only has to develop the skills (and courage), and have the proper tools on hand, to
 successfully determine where the problem is. After that, the problem can be repaired in short
 order. I'm going to try to explain in basic terms how to troubleshoot and repair an electrical
 problem. I know this will be very basic for some of us, but some of us didn't even know what
 a multimeter was, and those are the folks I'm writing this for.

In order to troubleshoot an electrical problem, one needs the basic tools. These tools are a
 multimeter, test light, and a good wiring schematic. The multimeter in it's basic form tests
 for resistance, voltage and amperage. Normally, in motorcycle maintenance, one doesn't utilize
 the ammeter as it measures only lower levels of amperage that will not be of value to us.
 However, testing for resistance and/or voltage is how we will determine where our electrical
 problem is. Multimeters are available in two styles, analog and digital. An analog meter 
simply uses a needle that swing over a scale of numbers. These numbers correlate to the voltage
 or resistance you are measuring. A digital meter will simply give you a digital number of the
 value of voltage or resistance. Either meter is acceptable. The analog meter is cheaper 
(as low as $13.00), but requires more concentration to use. The digital meter costs about 
twice as much, but is easier to use. I am going to assume that by the time you start using 
either type on your bike, you have read the manufacturer's instructions for the meter and 
are comfortable on how to set it up and calibrate it. It's quite easy. The test light is 
used to determine if you have voltage in a line. Basically all a test light is, is a twelve 
volt light inside a plastic case. Attached to one end of the light is an alligator clamp 
(that will be hooked to a ground on the bike). On the other end is a sharp point. All one 
has to do is hook up the test light (alligator clip to ground) and touch the tip to a 
components electrical hook up. If there is voltage there it will light, if not, then of course 
it won't. The sharp point is used to pierce the insulation of your wiring to determine if your
 wiring has voltage. It's much better however to try to restrain from piercing the insulation 
and find a connection to touch instead. The test light is not a crucial piece of test equipment
, however it is very cheap (less than $5.00) and when used with a multimeter, can be invaluable
. Both the multimeter and the test light can be purchased at auto parts stores, department 
stores and electrical or electronic supply stores (such as Radio Shack). Probably the scariest
 tool to use is the wiring schematic. Wiring schematics are normally a part of a service manual
. Service manuals are available from many sources (such as the motorcycle manufacturer, Clymer,
 and Haynes). Your best manual will be from the motorcycle manufacturer, but it costs more.
 However, don't take what's inside a service manual for gospel. I have found mistakes in
 manuals from all sources. Also some manuals covers different models, make sure you are using 
the schematic for your bike. When you open up the service manual to the wiring schematic for 
the first time, it will probably make you want to think twice before proceeding . There's a 
lot of information given in a small amount of space. But if you take one circuit at a time, 
you'll find it relatively easy to use, even for a beginner. But instead of looking at the 
overall wiring schematic, we're just going to follow a small part. It may seem difficult to do
 at first, but I promise the more you do it, the easier it will become.

The first time you solve a problem and fix it yourself, you have just paid for your test 
equipment over the cost of having a shop do it for you.

(Note: Before you start, I'd recommend that you bring your schematic to a photocopier and make
 several copies of it. By doing so, you won't have to worry about getting your service manual 
copy dirty, making it even harder to read. Also, you can use a colored pencil on a copy, 
making it much easier to follow.)

To demonstrate what I mean, pick an electrical component, say the headlight is not working on 
low beam. I'll be using the wiring schematic for my bike (1979 Harley Lowrider), most bikes are
 wired basically the same though the wiring colors may differ and the newer bikes have more 
electronics to contend with. First set up and zero your ohmmeter by touching the leads together
. The meter should go to zero or close to it. We're only looking for continuity, we're not real
 concerned with the actual values, in other words, you've either got continuity, or you don't.
 Note that you cannot read voltage with the multimeter set up for reading resistance. To do so
 may damage the meter. I would take off the headlight, and using the ohmmeter, I would hook the
 black lead to the headlight terminal that the ground (black) wire was attached to. Then put 
the red lead from the multimeter wire on one of the other terminals (in my case yellow or white)
 and check for continuity. Then swap to the third connection. If either lead shows infinity on
 an analog meter (the symbol for infinity looks like the number "8" on its side) or 0.L on your
 digital meter (your meter may read something different, check with the instructions that came 
with your meter), you've probably just found your problem. What basically happened was the 
multimeter's built in power source sent a small current through the wire and read how much
 power was received back in the meter and transferred this quantity of electricity to a way we
 can read it (by the needle or digital readout). If the filament inside the light is blown, 
the power didn't make it back to the meter, and therefore could not be read. But let's not
 make it that easy, we'll say the headlight checks out. Next we'll want to make sure we have a 
good ground. Leaving the black lead grounded, stick the red lead into the ground side of the 
headlight grounded. You should have continuity, if not, that's your problem. But since we've 
got the problem that the low beam is not working, but the high beam is, then that's probably 
not going to be the problem. Now we're going to establish that we have power going to the 
headlight. Change your multimeter over to a voltmeter and turn on your lights. With the black 
lead again grounded and the red lead in one of the headlight connectors, check for voltage. 
You should have 12 volts reading on the meter. If not, switch you dimmer switch and that should
 give you the 12 volts. Then do the same for the other wire. Let's say that we don't have power
 to the white lead. We'll just keep going back on our wiring schematic. On my bike the next 
component is the dimmer switch. I'd have to take apart my handlebar controls to get to it. 
Once there, you'll find three wires attached to the switch. In my case, I have the yellow and
 white wire that goes to the headlight and a blue wire that is the power wire. First with the
 black lead of the meter still grounded, touch your red lead to first the power lead to 
establish that you have power. In actuality, it's a known that you do, because you did have 
power to one of the leads at the headlight connection. But for practice, we'll do it now.
 You find you have power there, so you touch the lead to the switch connection and find you 
don't have voltage. Flip the switch to make sure you are trying to send power to that side of 
the switch. If not, you've just established that you have a bad dimmer switch. If you do have
 power, then you can pretty well figure you have an open wire between the headlight and the 
switch. All you have to do is repair or replace the wire. If during your troubleshooting of a
 problem you find a component (such as a solenoid, relay or simple switch) is not working, 
simply go into the electrical portion of the service manual and for most parts the manual will
 explain the troubleshooting procedure for that part, in detail.

I'm not going to try to get into soldering. Although it's easy to do, it takes practice to make
 it right. What I am going to do is recommend that you stay away from solderless connectors,
 especially butt connectors. They will give you a lot of grief because if you don't crimp them
 proper, they won't give a good connection and will give you intermittent problems that are a
 bear to troubleshoot. I would (and do) use solderless terminals only if you go ahead and
 solder them. Take the time and do it right, by either replacing the wire in it's entirety or
 by soldering the splice and either use electricians tape or heat shrink tubing.

A side note here is that if a parts and diagrams manual is available for your bike, buy it.
 It is invaluable in at least three ways. It can aid in disassembly/assembly of a component;
 it shows what 
parts are available to a component (verses buying the complete component) and it allows you to
 not have to depend on the parts counter person to sell you the proper part. You can go 
equipped with the part number and it will give you the correct part, quicker. I'd also 
recommend that you buy a service manual for every vehicle you own. Just one repair made by 
using the manual will more than pay for the manual itself. Don't be satisfied with just one 
manual for your vehicle. Sometimes a service manual from a different manufacturer will 
contradict another, or may give you another way of doing a procedure.