Coolant Level Sensor Circuit - Test - Perkins M190C Troubleshooting Manual

126
Troubleshooting Section
•
Not OK – The resistance is more than ten Ohms.
There is an open circuit or excessive resistance in
the circuit. There may be a problem in a connector.
Repair: Repair the wiring and/or the connector.
Replace part, if necessary. Verify that the problem
is resolved.
STOP.
Test Step 5. Check the Mini Marine Power
Display
A. Connect the mini marine power display to another
engine.
B. Operate the engine and monitor the mini marine
power display.
Expected Result:
The mini marine power display operates properly.
Results:
• OK – The mini marine power display operates
properly on another engine.
Repair: Connect the display to the original engine.
If the display operates correctly, there may be
a problem with an electrical connector. Refer to
the diagnostic functional test Troubleshooting,
"Electrical Connectors - Inspect".
If the display does not operate correctly on the
original engine, there may be a problem with the
ECM.
If the display does not operate correctly, replace
the ECM. Refer to electronic troubleshooting
Troubleshooting, "Replacing the ECM".
STOP.
• Not OK – The mini marine power display does not
operate properly on another engine.
Repair: Replace the mini marine power display.
Verify that the problem is resolved.
STOP.
Coolant Level Sensor Circuit
- Test
System Operation Description:
Use this procedure to troubleshoot any suspect
problems with the coolant level sensor.
The coolant level sensor monitors the engine coolant
level in order to warn the operator in the event that
the coolant level is low. The coolant level sensor is
located on the side of the expansion tank.
Illustration 28
Typical example of a coolant level sensor
(1) Sensor
(2) Brass rod
(3) Plastic cover
Coolant level sensor (1) contains no moving parts.
The sensor detects variations in capacitance. The
sensor's probe contains a brass rod (2) that is
covered with plastic (3). The brass rod is one plate
of a capacitor. The plastic cover is the capacitor's
dielectric. The coolant is the other plate of the
capacitor.
When the probe is immersed in coolant, the sensor
senses a particular capacitance. The sensor
responds by creating a short circuit between the
signal wire and the ground wire.
When the probe is not immersed in coolant, the
capacitance value changes. The change in the
capacitance value is detected by the sensor's
electronic circuits. The circuits apply approximately
+5 VDC to the signal wire. The ECM detects the
voltage and the ECM activates either a E2143-1 or a
E2143-2 event code.
The event codes are probably caused by a low
coolant level. The next likely cause is a problem with
a wiring harness or with the sensor. The least likely
cause is a problem with the ECM.
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