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3.8.
Activating components with a positive (+) voltage within the vehicle's electrical system (fig.8).
3.8.1.
set the selection switch to 'test' position.
3.8.2.
contact the probe tip to the positive terminal, the test indicator should illuminate Green. Whilst observing the test indicator, quickly
press and release the power switch to the single bar 'PositiVe' position.
3.8.3.
If the test indicator went off instantly, the unit has been overloaded. This could happen for the following reasons:
a) the tip's contact went to direct earth.
b) the component has a short circuit.
c) the component is a high current component (i.e. starter motor)
WarNiNG! randomly applying voltage to certain circuits can cause damage to a vehicle's electronic components. it is strongly
‰
advised to use the correct circuit diagram and diagnostic procedures whilst performing this test.
3.9.
Activating components with a negative(-) voltage within the vehicle's Electrical system (fig.9).
3.9.1.
set the selection switch to 'test' position.
3.9.2.
contact the probe tip to the negative terminal of the component, the test indicator should illuminate red. Whilst observing the test
indicator, quickly press the power switch to the double bar 'neGAtiVe' position and release it. if the indicator changes instantly from
red to Green, you may proceed with further activation.
3.9.3.
If the indicator went off instantly, the unit has been overloaded. This could happen for the following reasons:
a) Where the tip of the tester has contacted is a direct positive voltage.
b) the component has a short circuit.
c) the component is a high current component (e.g. a starter motor).
WarNiNG! With this function a vehicle's fuses may blow when the probe tip is earthed in series with them.
‰
3.10.
cHecKiNG For baD eartH coNtacts (fig.10).
3.10.1.
set the selection switch to 'test' position.
3.10.2.
Probe the suspected earth wire or contact with the probe tip. observe the colour of the test indicator.
3.10.3.
Press the power switch to the single bar 'PositiVe' position and release it. if the test indicator changes from Green to red, this is not
a true earth.
3.10.4.
if the test indicator turned off when the power switch was pressed to the single bar position, this circuit is more than likely a direct
earth. Note that high current components such as a starter motor will also cause the test indicator to turn off during this check.
3.11.
following and locating short circuits. in most cases a short circuit causes a fuse to blow. this is the best place to commence the fault
finding process.
3.11.1.
set selection switch to 'test' position.
3.11.2.
remove the blown fuse from the fuse box. Hold the probe tip against each of the contacts in turn whilst moving the power switch to the
forward, single bar 'POSITIVE' position. The side of the fuse housing which causes the test indicator to turn off when the power switch
is pressed forward is the shorted circuit.
3.11.3.
make a note of this wire's identification code or colour. Follow the wire as far as you can along the wiring harness.
3.11.4.
locate the colour coded wire in the harness and expose it as much as possible.
3.11.5.
Probe through the insulation of the wire with the probe tip and move the power switch to the forward, single bar 'PositiVe' position to
energise the wire. If the test indicator turns off, this wire can be identified as the shorted wire.
3.11.6.
continue testing the wire at each connector in the harness. The connector which causes the test indicator to turn off will lead you to
the shorted area. Inspect the harness for signs of chafing or burnt out wiring and replace or repair as necessary.
© Jack sealey limited
fig.8
fig.10
Original Language Version
fig.9
PPVt
issue 2 (H, f) 23/02/18
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