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62-11637
4–2
The engine start sequence consists of periods of time
with the engine preheater (EPH
−
power from 3MM
−
14
through PCM
−
27 to EPHT) and starter (SM
−
power
from 3MM
−
12 to SS, closing the SSC contacts) ener-
gized and de-energized for up to three start attempts
(see
), the pre-heat time varies in duration
based on engine coolant temperature (see
).
Figure 4.1 Auto Start Sequence
If the A00129 - “CHECK ENGINE COOLANT SEN-
SOR” alarm is active, the ambient temperature sensor
will be used. If both the A00129 - “CHECK ENGINE
COOLANT SENSOR” alarm and the A00121 - “CHECK
AMBIENT SENSOR” alarms are active the control sys-
tem assumes a temperature of less than 32°F (0°C) for
the preheat timing.
During the last five seconds of preheat
OR
for 5 sec-
onds before a start attempt, if no preheat is required,
the buzzer (B) is energized; then the starter solenoid
contactor (SSC) will be energized for a maximum of ten
seconds while the engine condition is checked during
the cranking period. The engine is considered to be
running, and the start sequence will be stopped, when
engine speed is greater than 1000 rpm and the engine
oil pressure switch (ENOPS) is closed.
During the second and third attempts, the control sys-
tem will monitor additional inputs.
• When engine speed reading is less that 1000 rpm,
ambient temperature is above 32°F (0°C) and the
ENOPS is closed - the A00130 - “CHECK
ENGINE RPM SENSOR” alarm will be activated
and the engine will be considered running.
• When engine speed reading is less that 1000
rpm, ambient temperature is below 32°F (0°C),
the ENOPS is closed and DC current is more
than 2 amps - the A00130 - “CHECK ENGINE
RPM SENSOR” alarm will be activated and the
engine will be considered running.
Once the engine is considered running, the control sys-
tem will keep the preheater energized for an additional
0 to 180 seconds of Post Heat, depending on engine
coolant temperature (refer to
During the start sequence the control system monitors
engine speed while cranking. If engine speed drops
below 50 rpm for three seconds the starter solenoid
contactor will be de-energized and the A00035 -
“CHECK STARTER CIRCUIT” alarm will be activated.
If the unit fails to start after three start attempts, the
A00031 - “FAILED TO START-AUTO“ alarm will be
activated.
If the unit is equipped with a fuel heater, the control
system will monitor ambient temperature. If ambient is
below 77°F (25°C) the fuel heater relay (FHR) will be
energized. Energizing FHR closes its normally open
contacts to supply power from fuse F14, through the
fuel heater temperature switch (FHTS) to the heater.
Refer to
for FHTS settings.
4.3.2
Transition To High Speed
After a successful start, the control system may call for
the engine to transition to high speed. When high speed
is required, the main microprocessor will provide a signal
through the CAN system to the ENCU, calling for the
speed change. Three factors control this transition.
• First: transition may be delayed if a time value is
entered in the HIGH SPEED DELAY Configura-
tion. The delay may be set to 0 to 10 minutes. The
factory default setting is 1 minute.
• Second: if the engine is started when the coolant
temperature is 79°F (26°C) or below it will remain
in low speed until the coolant temperature reaches
79°F (26°C) or it has operated for a minimum of 15
seconds. Once the coolant temperature reaches
79°F (26°C) the engine may transition to high
speed.
• Third: transition will be based on the need for tem-
perature control. Generally, the engine will operate
in high speed when the unit is in Pulldown or Pull-
Up Mode (full capacity required) and in low speed
when less than full capacity is required.
Table 4–1 Engine Preheat Time
Engine Coolant
Temperature
Heat Time in Seconds
Preheat
Post Heat
Less than 33°F (1.0°C)
30
180
33°F to 51°F (1.0°C to
11°C)
20
120
51°F to 78°F (11°C to 26°C)
10
60
Greater than 78°F (26°C) 0
0
0
PREHEAT
(If required)
FIRST
ATTEMPT
SECOND
AND
THIRD
ATTEMPTS
15 Seconds
STOP
3 to 10
Seconds
0 to 30
Seconds
PREHEAT
(If required)
ENGINE
RUNNING
(preheat)
CRANK
(with preheat)
5 SEC. BUZZER
5 SEC. BUZZER
0 - 180
Seconds
following start
0 to 30
Seconds
0 - 180
Seconds
following start
3 to 10
Seconds
ENGINE
RUNNING
(preheat)
CRANK
(with preheat)
Summary of Contents for Transicold X4 7300
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