Suzuki DF150 Service Manual page 71

3-12 ENGINE CONTROL SYSTEM
TPS (Throttle Position Sensor)
The TPS is installed on the throttle body and detects the degree
of throttle opening. The throttle shaft is interlocked with the TPS
shaft.
This sensor is a variable resistor changing resistance (Ohms) in
accordance with the throttle opening.
The varying resistance value is converted to voltage and input to
the ECM.
Based on the TPS voltage, the ECM calculates the idle position
and throttle opening and determines the control modes of vari-
ous controls systems (Idle air control, VVT system control, Fuel
injection control system, etc.).
NEUTRAL SWITCH
The neutral switch is installed on the throttle lever holder 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, no power is supplied to starter motor relay preventing
starter motor engagement.
(Start-in-gear protection. See page 3-45.)
SPS (Shift Position Sensor)
The SPS is installed on the throttle lever holder and detects the
shift position. The clutch lever is interlocked with the SPS shaft.
This sensor is a variable resistor that changes resistance (ohms)
in accordance with the shift position.
The varying resistance value is converted to voltage and input to
the ECM.
Based on the SPS voltage, the ECM calculates and determines
the change of shift position and executes the following controls.
• When the shift is in neutral, fuel injection is controlled to pre-
vent engine speed from exceeding 3 000 r/min.
• After shifting into forward or reverse from neutral, the IAC
valve is controlled to increase intake air for 0.1 second to pre-
vent unstable engine idle or stalling.
1. Throttle position sensor
Neutral switch
Shift position sensor
1