Suzuki DF 40, Service Manual

Page: 62 / 405

3-7 ENGINE CONTROL SYSTEM
SENSOR AND SWITCH
CKP (Crankshaft Position) SENSOR
There are three (3) CKP sensors installed below the flywheel
rotor.
When the reluctor bar on the flywheel passes the sensors, a
signal (voltage pulse) is generated and sent to the ECM.
This is the fundamental signal used to judge the engine speed
and crankshaft angle.
CMP (Camshaft Position) SENSOR
A CMP sensor mounted on the cylinder head cover and a
reluctor bar pressed onto the end of the intake camshaft are
used to detect piston position. The signal from this sensor is
received by the ECM which uses it to determine sequential
fuel injection control.
The CMP sensor contains a “Hall Effect” semiconductor and a
magnet. The semiconductor generates a voltage in proportion
to the line of magnetic force passed through it. When the single
trigger vane on the camshaft reluctor aligns with the sensor’
internal magnet, a large amount of magnetic force is gener-
ated allowing a high voltage to pass through the semiconduc-
tor. When the trigger vane moves away from the sensor, no
magnetic force is generated and low voltage passes through
the semiconductor.
These generated voltages are rectified to create “ON” (high
voltage) & “OFF” (low voltage) signals for ECM. The “ON” volt-
age signal indicates the position of #1 piston. The position of
#2 and #3 pistons, “OFF” signal, follow in firing sequence or-
der based on the now established position of #1 piston.
“Hall Effect”
semiconductor
Camshaft
Trigger vane
Magnet
CMP sensor
High voltage
Low voltage