Yanmar 4JH2E Service Manual page 357

Chapter 9 Electrical System
9.
Tachometer
~~~~~--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~4JH
Series
9·3 Measurement of sensor unit characteristics
(1) Measurement of output voltage
Synchroscope
Output voltage
Measuring conditions
Number of teeth of
ring gear
Gap between the ring
gear and sender
Resistance
Speed of ring gear
Measuring temperature
Measuring instrument
9.4
Fault
Does not function well.
1) Pointer does not move.
2) Functions intermittently.
1.0V
or
higher
9 9
IV or higher
20kQ
AC 100V
•Check the output wave pattern and number of pulses
when carrying out the output voltage measurement.
127
(2)
Measurement of intern•I resistance
1.3mm (0.0511 in.)
Measuring conditions
20kQ
Measuring temperature
500 rpm (approx. 800Hz)
Measuring instrument
20°C (68'F)
Synchroscope
Rotation detecting sender
Diagnosis
Check if there is an open-circuit cable connection at the
rear of the meter, a loose or disconnected terminal, or bad
continuity due to corrosion.
Disconnect at the instrument terminals, and measure the
voltage between the cable terminals. (To be 10"' 16V)
Satisfactory
9-46
Yes
No
20'C (68'F)
Digital tester
Digital tester
1.000
I
kn
Remedy
AC 100V
Make good the connection.
If the input voltage is
abnormal, check the cause.
(e.g. short-circuit, disconnec·
lion, or blown fuse, etc.}
Printed in Japan
AOA1029·9002