Engine Starter Circuit Description - Nilfisk-Advance SW8000 Service Manual

Service Manual – SW8000 Engine System, Gasoline/LPG 96
The DEPR controls the fuel flow, and provides the correct air/fuel mixture to maintain performance and
emissions control. The DEPR uses an internal computer, and fuel pressure and temperature sensors to
provide input to the ECM for fuel calculation, fault detection and diagnostics.
The Mixer Assembly is a self-contained air/fuel metering device that utilizes a relatively constant pressure
drop to draw fuel into the mixer from cranking to full load. The Mixer Assembly is mounted in the air
stream, ahead of the ETB.
The ETB uses an electric motor, connected to the throttle shaft, to increase or decrease the angle of the
throttle blade. The ECM sends electrical signals to the motor in the ETB to increase or decrease the airflow
to the engine to control the engine speed.
Note: For a more detailed and thorough description of the Gasoline and LPG fuel systems, refer to
the Diagnosis Manual ECM System WG1605 9Y110-01760.pdf.

Engine Starter Circuit Description

The starter is prevented from engaging whenever the drive pedal is NOT in the neutral position. A "Neutral
relay" (K4) is in series between the key switch and the starter solenoid. When the relay is at rest (not
energized) current is allowed to flow through the normally-closed contacts (30 to 87a) on to the starter.
The Main Machine Controller monitors the Drive Pedal Sensor to understand the current pedal position.
If it senses that the drive pedal is NOT in the neutral position, it energizes the neutral relay to break the
connection between 30 and 87a. This prevents the starter from engaging.
Crank
Starter Solenoid
Neutral Relay K4
Drive Pedal
Sensor Input =
Neutral
Main Machine Controller