Perkins UA Workshop Manual page 195

14
700 Series
To check Operation 14-4
To check power supply and continuity
1 Disconnect the glow plug connection.
2 Apply one probe of a multi-meter, that can check continuity, to the terminal of the glow plug and apply the
other probe to a suitable earth. If the continuity is correct the multi-meter will give an audible signal. If there is
no audible signal, renew the glow plug. Repeat this check for all of the glow plugs.
3 If a multi-meter is not available, connect a 12V test lamp between the positive terminal of the battery and
earth to check that the lamp will light.
4 Connect the test lamp between the terminal of the glow plug, that is furthest away from the power supply,
and earth. Operate the control switch and the test lamp should be illuminated if the power supply is correct.
5 Disconnect the cables at each glow plug.
6 Connect the test lamp to the positive terminal of the battery and to the terminal of a glow plug. The lamp will
be illuminated if the continuity is correct. If the test lamp is not illuminated, renew the glow plug.
7 When all of the glow plugs have been checked, connect the cables to the glow plugs.
To check the operation of the glow plugs
1 Disconnect the power supply cable and the connection cables from the terminals of the glow plugs.
2 Connect a 50-0-50 ammeter between the power supply cable and the terminal of a glow plug. Connect a
voltmeter between the glow plug terminal and earth.
3 Engage the control switch and check the readings of the ammeter and the voltmeter.
Iskra glow plugs
With a 12 volt supply, there should be an initial current of approximately 12.5 amperes, that should reduce to
approximately 7 ± 1 amperes after 30 seconds for UA and UC engines. For UB engines, the initial current
should be approximately 12.5 amperes, that should reduce to approximately 6.5 ± 1 amperes after 30 seconds.
Beru B80 glow plugs
With a 12 volt supply, there should be an initial current of approximately 25 amperes, that should reduce to
approximately 7 ± 1 amperes after 30 seconds for UA and UC engines. For UB engines, the initial current
should be approximately 25 amperes, that should reduce to approximately 6.5 ± 1 amperes after 30 seconds.
If the ammeter reading is low or there is no reading, renew the glow plug. If there is no voltmeter reading, check
the switch and the power cable.
When all of the glow plugs have been checked, remove the ammeter and the voltmeter and connect the power
supply cable. Check that the glow plugs have been connected correctly.
Workshop Manual, TPD 1392E, issue 3 183
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