Tracing Circuits - Triumph Rocket III Classic Service Manual

General Information
connector pins. An additional number outside the box will
identify the component.
LED (Light Emitting Diode)
Triumph use LEDs for the alarm warning light, instrument
illumination and warning lights, gear change lights and
rear light/brake lights on various models.
Motor
An electric motor. This could be the starter motor or a
motor within an actuator, for example within the ABS
modulator.
Relay
A relay is effectively an electromagnetic switch. To close
the relay contacts and complete the circuit, an
electromagnet in the relay is energised which causes the
relay contacts to close, making the circuit complete.
Relays are used when the electrical current is too great for
a mechanical switch, usually when the switching must be
done quickly to prevent arcing across the switch contacts.
If a mechanical switch were used, the mechanical switch
contacts would quickly burn away.
Resistor
A device placed in a cable to reduce a voltage or restrict
the maximum current a device can draw.
Splice
+
A hard cable joint where two or more cables are joined in
the wiring harness. A potential source of both open and
short circuits.
Switches
Normally
Open
~o
or
o
0
Normally
Closed
0--0
or
o
0
Change
Over
o
0
or
'" "
,,0
Cf
0
A mechanical device for completing or breaking a circuit.
There are three common types of switch: Normally open,
normally closed and change-over.
Tracing Circuits
The following is a description of two types of common
electrical failures, and some of the methods which may be
used to find them.
Open circuit
1
~Breakl
A break in an electrical circuit - current cannot flow.
Usually caused by a break in a wire or cable or by a loose
connection. Open circuits can often be intermittent,
making diagnosis difficult.
Short circuit
A 'short cut' in an electrical circuit - current by-passes the
intended circuit, either to earth or to another, different
circuit. Often caused by failure of the cable insulation due
to chafing or trapping of the wire. There are two different
types of short circuit - short to ground and short to Vbatt.
A short to ground means that the current is going to earth
before it reaches the component it is supposed to feed.
These are often caused by chafing of the harness to the
frame or wires trapped between a bolted component, and
will often blow the fuse on that circuit.
A short to Vbatt is a short to battery voltage (12 Volts>
and is caused by a live power supply wire contacting an
adjacent cable. Note that it is also possible for a 5 Volt
sensor reference voltage to short to an adjacent circuit,
1.16
SelVice Manual - Rocket III I Classic I Touring