BOMBARDIER Johnson 90 Service Manual page 69

ENGINE CONTROL SYSTEM
COMPONENTS FOR SYSTEM CONTROL
CTP (Closed Throttle Position) SWITCH
The CTP switch is installed on the bottom of throttle body
and used to detect whether the throttle is fully closed or not.
This switch is "ON" at closed throttle and "OFF" at any open
throttle position. Based on the switch throttle position signal
input, the ECM determines the control modes for various
control system (idle air control, ignition timing control, etc.).
NEUTRAL SWITCH
The neutral switch is installed on the cylinder block (STBD
side) and used to detect the shift position.
This switch is "ON" in neutral and "OFF" in forward or
reverse. Based on the switch shift position signal input, the
ECM performs the following controls:
• When the shift is in forward or reverse at the time of engine
start, the fuel injection function is cancelled. (Start-in-gear
protection. See page 3-29.)
• When the shift is in neutral, fuel injection is controlled so
that the engine speed does not exceed 3000 rpm.
• When the shift is in neutral, if the engine speed exceeds
900 rpm, ignition timing is fixed at BTDC 8º.
• After shifting into forward or reverse from neutral, the IAC
valve is controlled to increase intake air for two seconds 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, injec­
tor, ignition coil, IAC valve, CMP sensor and high pressure
fuel pump.
3-9