Mack CHM 2010, Operator'S Handbook Manual

Page: 139 / 232

OPERATION 131
V-MAC IV Shutdown Option: Idle Cooldown
This feature provides a means of cooling down the engine and turbocharger. If the idle
cooldown option is enabled using VCADS Pro MACK Support Software and the system
senses that the turbocharger may be hot, the engine will not shut down when the vehicle
stops, the parking brake is set and the key switch is turned to the OFF position. This feature
allows the driver to lock the truck and walk away while still providing adequate cooldown.
All switched accessories will then turn off once the engine has stopped. If this option is set,
the engine can be shut down immediately by cycling the key switch.
The idle cooldown timer is set to 3.5 minutes as soon as the engine load exceeds 25%,
provided that the engine has been running at least 60 seconds. After the load drops below
25%, the timer begins counting down. If the key switch is turned off before the timer
expires, the engine will continue to run until the timer reaches zero.
If a pyrometer is installed, the idle cooldown function will use the pyrometer reading,
shutting the engine down when the temperature drops below 232°C (450°F), or after 3.5
minutes, whichever comes first.
The default for this option is set at OFF from the factory.
Note: The parking brake must be on for the idle cooldown function to work.
Engine Shutdown System (If Enabled)
The engine is protected by a system that prevents engine damage by shutting down the
engine whenever a potentially damaging condition (such as loss of oil pressure, loss of
coolant or engine overheating) is detected. If the system detects such a condition, a warning
indicator light and an alarm will alert the driver before the engine actually shuts down.
Engine Shutdown Indicator — During normal operating conditions, this indicator should
illuminate as soon as the key switch is turned on. After the engine is started, it will remain
illuminated until engine oil pressure reaches normal idling range. During shutdown, if the
system detects a condition that could lead to engine failure, the Engine Shutdown indicator
will illuminate prior to engine shutdown.