LOFA MC536 Operation and Troubleshooting
6
Revision - A - 22-May-2006
Gauges
Voltmeter
The voltmeter is connected to the fuel run/stop solenoid output. If the voltemeter does not indicate in the run
position, this indicates a problem with the solenoid circuit. A battery voltage reading of approximately 14
volts on a 12 volt system (28 volts on a 24 volt system) while the engine is running indicates the battery is
charging properly.
Tachometer
The tachometer indicates engine RPM using a frequency signal derived from the engine. This signal may be
provided by an alternator frequency tap or proximity switch.
Note
If the alternator is not excited (not charging),
no frequency is generated and the tachometer will indicate 0 RPM.
The tachometer must be calibrated to accurately indicate RPM (see
Tachometer Calibration Instuctions
for
details).
Oil Pressure Gauge
The gauge measures oil pressure with a resistance sender on the engine referenced to ground. When a
sender/switch combination is used on the engine, the marking
G
generally indicates the gauge terminal. The
gauge expects a low resistnace for low pressure and a higher resitance for higher pressure. If the gauge is
not connected to the sender, the gauge will read full scale (pegged). A defective sender or shorting the
gauge input to ground will cause the gauge to read 0 pressure. When using sender/switch combinations,
swapping the
WK
and
G
terminal prevents the gauge from working and may cause spurious shutdowns.
Warning
Low oil pressure is an indication of engine wear,
not an accurate indication of low oil level.
Note
Senders and gauges must be matched to each other.
Improperly matched gauge/senders will not indicate correctly.
Most senders are grounded through the sender body.
Do not use insulating sealant (i.e. Teflon tape) when installing senders.
Temperature Gauge
The gauge measures engine temperature with a resistance sender on the engine referenced to ground.
When a sender/switch combination is used on the engine, the marking
G
generally indicates the gauge
terminal. The gauge expects a high resistnace for low temperatures and a lower resitance for higher
temperatures. If the gauge is not connected to the sender, the gauge will read 0. A defective sender or
shorting the gauge input to ground will cause the gauge to read fulle scale (pegged). When using
sender/switch combinations, swapping the
WK
and
G
terminal prevents the gauge from working and may
cause spurious shutdowns.
