Engine System, LPG
96
Service Manual – SC8000
Note that if the
Driver Box
sends a
START INHIBIT
signal from
J1-22
to the
K3 RELAY CONTROL SWITCH
to open the switch, no ground will be provided to the
START
relay coil
K3
, the
K3
contacts will not close
and no positive voltage will be sent to the
START COMMAND TO STARTER RELAY
.
• The drive pedal must be in the neutral position and the
Drive Pedal Sensor
must be in the deadband
range.
• For the engine to run:
• The
K2 RELAY CONTROL SWITCH
must remain closed to provide a ground to the
IGN
relay coil
K2
. This
keeps the
K2
relay contacts closed to maintain positive voltage to the
IGN. SW INPUT
.
• The
Coolant Temperature Output
must not provide an “overheat” signal to pin
J1-30
on the
Driver Box
.
The engine coolant temperature sensor is a temperature-sensitive resistor. If the engine coolant
temperature exceeds 225 degrees F. for more than five seconds, the Engine System senses the
threshold resistance in the coolant temperature sensor. The Engine System then provides a
Coolant
Temperature Output
signal to pin
J1-30
to generate a fault code and shut the engine off.
• The
Low LP Pressure Switch S5
must be open to indicate adequate LP fuel supply (LPG engines only).
Note:
LPG engines will continue to run for a few seconds after the key switch is turned off. This burns
any fuel remaining in the engine to prevent backfires the next time the engine is started. When the
key switch is turned off, the Engine System switches off the fuel supply to the engine, but keeps the
ignition system on until it senses that the engine has stopped running.
Engine Protection – Low Oil Pressure Shutdown
The engine controller monitors the oil pressure switch. If it sees a loss of oil pressure, it will shut down the
engine immediately.
Engine Protection – High Temperature
The engine controller monitors the engine coolant temperature. If the temperature reaches 230 deg. F. (110
deg. C.), it will derate the engine power by 30%. If the temperature reaches 240 deg. F. (115 deg. C.), it will
shut down the engine.
Engine Speed Control
The operator can request three engine speeds, “idle” (1200 RPM), “run” (2200 RPM) and “maximum”
(2400 RPM). The Engine Controller operates an Electronic Throttle Body to adjust and maintain engine
speed according to the requested input of the Main Machine Controller. To request the three different
engine speeds, the Main Machine Controller (Driver Box) uses two wires that are connected to the Engine
Controller. It either applies 0v or 12v to each wire to request the specific speeds. See table below.
Pin#
Wire
Color
Function
Voltage at
1200 RPM
Voltage at
2200 RPM
Voltage at
2400 RPM
J2-30 on Driver Box
GRA/BLU Input from Driver Box
0
0
+12 VDC
J2-29 on Driver Box GRA/ORN Input from Driver Box
0
+12 VDC
0
