ELECTRICAL EQUIPMENT 23A
Fault diagnosis
The alternator is designed in such a way that a flow
of current (indicated by no light at the warning light
or a reading shown on an ammeter) shows that the
system is in correct operation. If the system is in
correct operation, no open circuit, voltage or
current output checks need to be done on the
installation unless:
• The warning light does not show when the
alternator is stationary and the switch is in the "on"
position or it shows a light when the alternator is in
operation.
• No charge current is shown on the ammeter.
• The battery is discharged.
• The battery is hotter than normal which is an
indication of loss of voltage control.
If one or more of the above symptoms occur, the
procedure indicated below should be applied.
1 Ensure that the battery is fully charged.
2 Connect a moving-coil voltmeter of good quality,
with a range of 0-50 volts, across the positive and
negative terminals of the alternator. If an ammeter
is not fitted in the electrical circuit, fit a moving-coil
ammeter of good quality, with a range of 0-100
ampere, in the wire between the alternator and the
positive terminal of the battery.
3 Turn the warning light switch to the "on" position
(main switch on instrument panel); the warning light
should be illuminated.
4 Switch on a 10-15 ampere load, for example,
lights, fans, etc.
5 Start the engine and operate it at a fast idle
speed; either the warning light should be
extinguished or the ammeter indicates a small
change in the current in relationship to the engine
speed.
6 Increase the engine speed for a moment to near
maximum speed, when the charge current should
be approximately equal to the rating for the
alternator, as shown in the data and dimensions.
7 Operate the alternator at approximately half
speed (engine speed approximately 1500 rev/min)
and remove the electrical load. The voltage should
go up to 14 volts for a 12 volt system or 28 volts
for a 24 volt system and then remain constant. At
the same time the current reading should show a
reduction.
Any change in the above data can indicate a fault
and the procedure that follows should be used
before any components are disconnected. This
procedure is not suitable for A127 alternators and, if
a fault is found, the alternator should be removed
for test by a specialist.
The regulator is a sealed unit and a repair is not
possible. If there is a regulator fault, the regulator
must be renewed.
Perkins Phaser/1000 Series, April 1995 23A.05
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