TOHATSU 40 Service Manual page 227

SECTION 7
Half-Maximum RPM Limitation
The CD Unit will limit the engine speed to about half the maximum
RPM when the overheat sensor, water pressure sensor, or oil level
sensor signals an abnormal condition. Depending upon the model
of the engine, one, two or all three sensors are provided.
Description of Operation for models 40 / 50 / 60 / 70 / 80 / 90
Engines
In these engines, the water pressure sensor (1) and overheat
1
sensor (2) control the half-maximum RPM limitation input
[terminal (9)] to the CD Unit (4). When either, or both, of these
sensors detect an abnormal condition (see Section 4), the half-
maximum RPM limitation input goes low and the CD Unit limits the
engine speed to about half its maximum RPM. At the same time,
the abnormal condition also activates the warning horn (6). Note
that the oil level sensor (3) only activates the warning horn and the
oil level light (17) in the tachometer (5) because the diodes (15)
block the signal from CD Unit.
7-48
T1487
3-/ 4-Cylinder