Suzuki DF 40, Service Manual

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3-9 ENGINE CONTROL SYSTEM
NEUTRAL SWITCH
The neutral switch is installed on the cylinder block (PORT
side) and used to detect the shift position.
This switch is “ON” in neutral and “OFF” in forward or reverse.
The ECM detects shift position and performs the following con-
trols :
• Fuel injection is not performed when the shift is in forward or
reverse at the time of engine start.
(Start-in-gear protection)
• When the shift is in neutral, fuel injection is controlled so that
the engine speed does not exceed 3000 r/min.
• When the shift is in neutral, if the engine speed exceeds
1200 r/min, the ignition timing is fixed at BTDC 9°.
• For two seconds after shifting into forward or reverse from
neutral, the IAC valve is controlled so that intake air increases
to prevent unstable engine idle or stalling.
ECM MAIN RELAY
The ECM main relay is installed in the electric parts holder.
When energized by the turning ignition switch ON, it forms the
circuit which supplies battery voltage to the ECM, injector, igni-
tion coil, IAC valve, CMP sensor and high pressure fuel pump.
CTP (Closed Throttle Position) SWITCH
The CTP switch is installed on the top of throttle body and
used to detect whether the throttle is fully closed or not.
This switch inputs the signal to the ECM. The ECM detects the
throttle position and determines the control modes for various
control system (idle air control, ignition timing control, etc.).