Descent Control Mode
Note: Before engaging descent control, determine an appropriate speed for the vehicle’s load and grade of the road.
Descent control mode attempts to keep the vehicle speed at the set speed using all available engine brake stages when descending a grade.
To activate descent control mode:
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Exit cruise control.
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Remove your foot from the accelerator pedal.
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Set the engine brake to any of the three 'on' positions (positions 1, 2, or 3 in Fig.).
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Use the set or resume buttons to set the vehicle speed.
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Position 0: Off
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Position 1: Low
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Position 2: Medium
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Position 3: High
Fig. 1, Descent Control Mode Engine Brake Positions
The descent control mode active telltale illuminates on the driver display when descent control mode is active. See Fig..
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Descent Control Mode Active Telltale
Fig. 2, Descent Control Mode Telltale, ICUC
In descent control mode, all three levels of engine braking will be employed to keep the speed below the set speed regardless of the level selected by the right-hand stalk switch.
In the case of very steep road grades, the engine brake may not be able to maintain the vehicle speed. The driver may apply the service brakes without dropping out of descent mode to slow the vehicle. If the vehicle is slowed below the set speed, this lower speed will become the set speed after the driver releases the service brakes. In this instance, a pop-up window in the ICU will notify the driver a new set speed was captured as shown in Fig..
Fig. 3, Descent Mode Speed Set Notification, ICUC
Descent control mode will not keep the speed above the lower limit of the set speed, so it is possible to eventually coast to a stop, unless the stalk lever is moved to 'off' (position 0), or the accelerator pedal is applied.
After accelerator pedal application, descent control mode is resumed.
Moving the lever to the 0 position deactivates descent control mode and resumes cruise control, using the descent control set speed as the cruise control set speed.