FEATURES
Thermostat Mode
Thermostat Mode automatically stops and restarts the engine to maintain oil temperature, battery
voltage and cab temperature. For on-highway applications, Thermostat Mode is used to keep the
cab/sleeper (on-highway truck) and passenger area (coach) at the desired temperature and maintain
the Engine Mode parameters. The optional thermostat must be turned ON for Thermostat Mode to
be active. The Optimized Idle Active Light is illuminated whenever Thermostat Mode is active.
Engine mode parameters as well as the interior temperature are monitored in Thermostat Mode.
The thermostat informs the ECU when to start/stop the engine to keep the interior warm/cool
based on the thermostat setting. Ambient temperature is also monitored to determine if the
ambient temperature is extreme enough that the engine should run continuously.
Any accessories (HVAC fans) connected to the Vehicle Power Shutdown relay will turn ON for
Thermostat Mode engine starts. The HVAC fans will remain OFF for Engine Mode starts.
If Optimized Idle starts the engine for Engine Mode, and Thermostat Mode is then requested, the
HVAC fans will turn ON approximately 30 seconds after the Thermostat Mode is requested.
Thermostat Mode can be enabled for a maximum amount of time. After which, the engine will
ignore any requests from the thermostat.
Two automatic conditions which help keep the operator comfortable and reduce engine cycling
are Continuous Run Mode and Extended Run Mode.
Continuous Run Mode - This mode allows the engine to run continuously if the outside
temperature (determined by the skin temperature sensor or AAT Sensor if installed and
con
fi
gured) falls outside the hot or cold set limits and the thermostat set point can not be met. The
default set limits are 25°F (-3.9°C) for heat mode and 90°F (32°C) for cool mode. When a skin
temperature sensor is installed, these values are customer programmable in the thermostat and are
password protected. When an ATT Sensor is installed these limits can be set by DDDL or DRS.
When the thermostat is in the Continuous Run Mode, the thermometer icon will
fl
ash along with
the heat or cool icon on the thermostat if a skin temperature sensor is installed. If the thermostat
set point is satis
fi
ed, the engine will shutdown regardless of the outside temperature.
Extended Idle Mode - If the Continuous Run Mode is not needed and the thermostat set point is
not met within 45 minutes, the engine will shutdown for
fi
fteen minutes and restart and run for
fi
fteen minutes. This
fi
fteen-minute on and off cycle will continue until the thermostat set point
is reached or until the thermostat is turned off. This may be an indication that the heat or cool
setting on the thermostat does not match the vehicle heating or cooling system setting. It could
also be an indication of low freon, blockage in the heater system or system tampering.
Extended Idle Mode can be disabled with a customer selectable parameter. After running 45
minutes, the engine will shutdown instead of cycling at 15 minute intervals.
5.18.2
INSTALLATION
Optimized Idle utilizes the following inputs: Park Brake, Neutral Switch, Hood Tilt Switch, OI
Thermostat (optional), and Cruise Enable. Optimized Idle utilizes three digital outputs: Vehicle
Power Shutdown Relay, OI Alarm, and the Optimized Idle Active Light. A hardwired Vehicle
Speed Sensor is required. See see Figure 5-26 for the Optimized Idle overall system schematic.
5-108
All information subject to change without notice.
(Rev. 01/07)
7SA827 0701
Copyright © 2007 DETROIT DIESEL CORPORATION
