3-10 ENGINE CONTROL SYSTEM
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 per-
forms 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 3-33.)
• 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 900
r/min., ignition timing is fixed at BTDC
8°.
• 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, injector, ig-
nition coil, IAC valve, CMP sensor and high pressure fuel pump.
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 con-
trol system (idle air control, ignition timing control, etc.).
CTP s
witch
CTP switch
ECM main rela
yECM main relay
Neutr
al s
witch
Neutral switch
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