Optimized Idle®

SD DM 10.05.01

The optimized idle option on Detroit Diesel engines is a system that automatically stops and restarts the engine to accomplish the following:

  • Keep the engine oil temperature between 60 and 104°F (16 to 40°C)

  • Keep the battery charged

  • Keep the cab or sleeper at a constant, desired temperature (if equipped with a thermostat)

The benefits of the system include reduced engine idle time, fuel savings, reduction of exhaust emissions and noise, increased starter and engine life, and less chance of dead batteries due to electrical loads.

Optimized Idle operates in two modes; the engine mode or the thermostat mode. The engine mode keeps the battery charged and the engine oil temperature within factory set limits. The thermostat mode is the same as the engine mode, but also keeps the cab and sleeper at a constant preset temperature.

The engine mode is always activated when the system is operated. The thermostat mode is activated when the thermostat is turned on.

The thermostat mode controls the set point, which is the desired temperature of the cab and sleeper, and the comfort zone, which is the number of degrees from the set point before the engine needs to heat or cool the cab. There are three comfort zones: 4°F (2°C), 7°F (4°C), or 10°F (6°C).

Vehicles equipped with Optimized Idle have a label on the dash, and a telltale lens in the dash message center. See Fig. for the dash label detail. See General Information for the appropriate dash message center. If equipped with the thermostat mode, a thermostat is located in the sleeper, above the bunk. See Fig..

The thermostat consists of an LCD readout and four buttons.

Fig. 1, Optimized Idle Dash Label

  1. Down Button

  2. Up Button

  3. Upper/Lower Temperature Icon

  4. Temperature Display

  5. Degrees Fahrenheit Indicator

  6. Mode Button

  7. Cooling Icon

  8. Cool/Heat Selection Button

  9. Heating Icon

  10. Degrees Celsius Indicator

Fig. 2, Optimized Idle Thermostat

The display normally shows the temperature of the sleeper, but changes accordingly as the buttons are pressed.

The button functions are as follows:

  • Up Button: increases the set point and comfort zone.

  • Down Button: decreases the set point and comfort zone.

  • Cool/Heat Button: detects either cooling or heating operation.

  • Mode Button: scrolls through the various functions. It can also be used to set desired temperature values.

  1. Activate Optimized Idle (engine mode).
    1. Set the parking brake.
    2. If it is tilted, close and secure the hood.
    3. Start the engine and let it idle.
    4. Put the transmission in neutral.
    5. Turn on the cruise control. The dash light will begin blinking, indicating that Optimized Idle is active. The system is now in the engine mode and after an initial phase, in which the idle speeds up to 1000 or 1500 rpm (depending on the outside temperature), the engine will stop and start automatically to keep the battery charged and the engine oil warm. The dash light stays on and shines steadily at this point.

    2. Important: The cruise control must be turned on after the engine is idling. If it was previously turned on, turn off the cruise control, then turn it on again.

  2. Activate the thermostat mode (if so equipped).

      Note: When the system is in the thermostat mode, it is also in the engine mode. It will continue to operate in the engine mode even if the thermostat mode is turned off.

    1. With the system in the engine mode, set the cab and sleeper heater or air conditioner controls to the highest setting.
    2. Turn on the thermostat by touching any of the four buttons. See Fig.. The display will flash the current sleeper temperature and the previous mode (cooling or heating) selected. If the cab needs to be cooled or heated, the cool/heat icon will flash.
    3. Choose either cool or heat by pressing the Cool/Heat button. Make sure the selection matches that of the cab controls.

      4. Important: If the heat or cool selection of the thermostat does not match that of the cab, the system will idle and cycle excessively.

    4. Select Fahrenheit or Celsius by pressing and holding the Mode button until either the "F" or "C" is displayed.
    5. Select the temperature set point by pressing either the Up button or the Down button, as applicable. Holding the button will cause the display to count up or down rapidly. When the desired set point is displayed, release the button. The set point is stored in memory.
    6. Select the temperature comfort zone by pressing the Mode button until the upper and lower temperature limit icon is displayed. Then use the Up or Down button to select one of the three comfort zones of 4°F (2°C), 7°F (4°C), or 10°F (6°C).
  3. To change the display to either Fahrenheit or Celsius, press the Mode button until only the F° or C° icon is flashing. Press the Up or Down button to change to the desired value. The main display will appear five seconds after the button is released.
  4. To deactivate the thermostat mode and return to just the engine mode, press the Mode button and hold it for three seconds.
  5. To shut down Optimized Idle completely, either turn off the ignition or use the drive away feature. The drive away feature allows the use of all the engine features. Use the drive away feature as follows:
    1. If the engine is running: Release the parking brakes or put the transmission in gear. If the engine is not running: Start the engine. Release the parking brakes or put the transmission into gear.
    2. Let the engine return to base idle. The active light will turn off. Optimized Idle is now disabled and all the engine features are available.
Note:
Parent topic: Optional Engine Systems
Document Number: 0000123309
Manual Publication Date: 2025-01-23
Topic Publication Date: 2025-01-23