Rotax 912 i Series Maintenance Manual page 386

RESISTANCE MEASUREMENT (TEMPE-
RATURE SENSOR)
General note
If resistance values are measured with an ohm-
meter, all values are given at a temperature of
approx. 20 °C. A resistance value changes with
temperature.
The temperature sensors which are mostly used
in the engine are NTC (Negative Temperature
Coefficient) and operate in the opposite manner
i.e. the resistance value essentially falls when
the temperature rises. This must be taken into
account when measuring at temperatures which
differ from the specified values. The relationship
between the resistance and the temperature can
be found in the respective diagram of the rele-
vant trigger coil.
The resistance value of a temperature sensor
can appear to be in working order at ambient
temperature but defective at other temperatures.
If in doubt, replace the trigger coil.
It should be remembered that the static
NOTE:
measurement is only meaningful for the
determined temperature ranges. Exact
information can be obtained if the trigger
coil has been tested over a wider tempe-
rature range.
Fig. 20
R
R Ohmmeter
Effectivity: 912 i Series
Edition 1/Rev. 0
BRP-Powertrain
MAINTENANCE MANUAL
T
06342
T Temperature sensor
VOLTAGE MEASUREMENT
General note
NOTICE
WARNUNG
Voltage supply:
The secondary side of the ignition unit is an ex-
ception! The ignition voltage can be up to
30 000 volts!
This high voltage must only be measured with a
special measurement unit or an oscilloscope
with a special test probe.
Voltage can be detected with a simple test lamp
or a voltage tester. However, this only indicates
whether there any voltage is connected at all. To
check the level of the voltage present, a voltme-
ter (= multimeter) must be connected.
Step
1 The voltmeter must first be adjusted to the
measurement range in which the voltage
to be measured probably is. Voltages on
the engine are generally no higher than
approx. 28 volts.
2 Connect the cables of the measurement
unit parallel to the consumer.
Fig. 21
Voltage
V
supply
V Parallel-connected voltmeter
Procedure
R
06344
R Consumer
76-70-00
Page 16
July 01/2012