Oll. Pressure Sensor•Oxygen Sensor; Dc Circuit Breaker•Wb Oxygen Sensor; High/Low Rpm Shutdown; Exhaust Temperature Switch - Westerbeke 6.5 MCG Service Manual

COMPONENT TESTING
TESTING THE OIL PRESSURE SENSOR
The oil pressure sensor sends a DC voltage to the ECU that
the ECU interprets as oil pressure. Should this voltage fall
below a certain level, the ECU will shut the generator down
and illuminate the oil pressure LED:
Test the sensor by checking resistance (at rest):
Ohm Value· 240- 2700
ENGINE DC CIRCUIT BREAKER
The generator's engine DC circuit is protected by a rocker
type DC 20 amp
~reaker
mounted on the control box (this
also serves as an Emergency Stop Switch). Excessive DC
current draw or DC electrical overload anywhere in the
instrument panel wiring or engine wiring will cause the
breaker to trip to the OFF po~ition. In this event, the DC
power to the ECU will be intenilpted, stopping the generator.
No panel LED will illuminate. Check and repair the source
of the problem. Mter repairing the fault, reset the breaker and
restart· the generator.
HIGH/LOW RPM SHUTDOWN
The ECU monitors engine speed by the AC voltage produced
by the MPU. Should this voltage reach a preset value, the
ECU will interpret this as an engine overspeed (2175 rpm
approximately) ancJ.,open the K2 relay, stopping the
generator. The panel Overspeed LED will illuminate. Should
the MPU produce a low AC voltage that the ECU interprets
as an underspeed condition, the ECU will open the K2 relay
and stop the generator. The Overspeed LED will then blink.
TESTING THE OXYGEN SENSOR
Wide Band Sensor: Unplug the s_ensor from the engine .
harness. Locate Ute red pin lead and the vacant black pin
le~d.
Measure across these two pins with an ohm
~eter.
Resistance Value 110.0 - 130.0 OHM (approximately)
No continuity should
be
found between these two pins-and
any of the other four.
A sensor not meeting these tests is presumed faulty. Care
should be taken when installing a replacement sensor. Do
not scratch, damage or handle the sensor end in any way.
. TESTING THE EXHAUST TEMPERATURE SWITCH
An exhaust temperature switch is located on the water
injected exhaust elbow. Normally closed, this switch will
open and the ECU will interpret this as a high exhaust tern-
. perature and open the K2 run relay stopping the generator.
The exhaust temperature LED on the panel will illuminate.
The switch opens at 260- 270°F (127- 132°C}. This switch
resets (contacts close) at approximately 225°F (l07°C}.
When testing,.continuity should be found (switch is
· normally closed).
·
'1\t\~
WB OXYGEN SENSOR
The Wide Band 02 Sensor is installed in the exhaust
manifold. It signals the ECU that correct exhaust system
discharge is taking place.
TESTING RESISTANCE
COIL VALVE: - HEATER ELEMENT
GREY·WHITE 10 OHMS
J
,WIDE BAND SENSOR
/J
.'PM:049077 .
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&
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