Water Pressure Sensor - TOHATSU 40 Service Manual

SECTION 4

WATER PRESSURE SENSOR

The water pressure sensor is a pressure-sensitive switch
1
installed on the powerhead to monitor the forced water
cooling system. The sensor is connected in series with the warning
horn. If the sensor detects low water pressure at a predetermined
RPM, contacts close and cause the warning horn to emit a
continuous tone. The engine RPM limitation function is also
activated.
The water pressure sensor is standard equipment on
models 80, 90, 115, 120, and 140. It is available as
an option for models 60 and 70.
Function Test and Adjustment
Verify the lower unit water intake screens are not clogged before
testing a suspect water pressure sensor. Perform this test with the
engine in a test tank or on the boat.
Test and adjustment requires running the engine
in close proximity to the technician. To avoid
serious injury, keep wires, test equipment, tools,
and body parts away from powerhead linkage
and flywheel.
1. Remove sensor mounting screws (1) and disconnect the
2
sensor ground wire.
2. Disconnect the sensor bullet connector at the electrical box.
3. Using a continuity light or ohmmeter, connect one tester
3
lead to each sensor lead (2) and (3). Tester should indicate
continuity (switch closed).
4-12
NOTE
WARNING
T1171
T1172
T1173
3-/ 4-Cylinder