Perkins New 1000 Series Workshop Manual page 334

14
New 1000 Series
Fault diagnosis Operation 14-6
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:
l 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
l No charge current is shown on the ammeter
l The battery is discharged
l 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, refer to the Data and dimensions for "Alternators" on page
34.
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.
If the warning light is not illuminated when the switch is in the "ON" position:
Check the bulb. If no fault:
Check all the connections at the regulator, at the alternator and at the battery.
If no fault:
Turn the switch to the "OFF" position. Disconnect the wire from the "F" terminal on the alternator and connect
a wire between the "F" terminal and the negative terminal on the alternator. Turn the switch to the "ON"
position.
If the warning light shows, the fault is in the regulator.
If the warning light does not show, the fault is in the alternator.
Continued
320 Workshop Manual, TPD 1350E, Issue 4
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