Cruise Control
For added driver convenience and comfort, DDEC also features a Cruise Control option that works just like the system in your car. It can be operated in any gear above 1100 rpm or road speed faster than 20 mph (32 kph), up to the rated engine speed. It also can be programmed to hold your road speed at or below the maximum vehicle speed. The switch to energize Cruise Control is usually mounted on the instrument panel or steering wheel.
Engine speed and power are varied under Cruise Control to maintain the set vehicle speed. The vehicle speed must be above Min Cruise Set Speed and below Max Cruise Set Speed. It is recommended that Max Cruise Set Speed be set to the default to allow proper operation of other features such as Fuel Economy Incentive and PasSmart. The Vehicle Speed Limit should be used to limit vehicle throttle speed.
Turn the switch ON to energize the system. Remember as a check after each engine start, DDEC looks for a one-time activation of the clutch (if equipped) and service brake before DDEC allows Cruise Control to be enabled.
DDEC must also see or recognize that the Cruise Enable Switch has changed. If the Cruise Enable Switch is OFF it needs to be turned ON. If the Cruise Enable Switch is left in the ON position at key OFF, the switch must be cycled OFF then ON for DDEC to see a status change to allow Cruise Control activation. The status of DDEC inputs to activate Cruise Control at key ON is listed in the following table.
| Input Status to Activate Cruise Control | ||
|---|---|---|
| Input | Input Status at Key ON | Input Status Before Cruise Control Activates |
| Service Brake Switch | ON | OFF |
| Clutch Release Switch (Manual Trans. only) | ON | OFF |
| Cruise Control Enable Switch | OFF | ON |
Once Cruise Control is enabled and you reach your road speed, press the SET Switch to activate Cruise Control. The cruise light will come on. To increase road speed toggling the switch will result in a one mile-per-hour (1.6 kph) increase or decrease in vehicle speed. If Cruise Control has been disabled, toggling the RSM/ACC Switch restores the vehicle to the previously set cruise speed. , press the RSM/ACC Switch. To reduce road speed, press and hold the SET/CST Switch until the lower speed is reached.
Cruise Control can be overridden at any time with the throttle pedal if the vehicle is operating at less than the programmed Max Road Speed.
Cruise Control is deactivated by slightly pressing the service brakes, clutch pedal, or trailer brake. The ON/OFF Switch will also deactivate Cruise Control.
Cruise Control will maintain vehicle speed even on upgrades, unless power requirements demand a downshift. If the Cruise Control/Engine Brake function is turned ON, the Cruise Control will limit your speed on downgrades. Most likely, Cruise Control will feel stronger than driving with the accelerator pedal because of the instantaneous and wide-open throttle response. That's why Cruise Control use is not suggested during slippery driving conditions.
Use Cruise Control after downshifting on a hill to pull the hill. Hitting the RSM/ACC Switch (not the SET Switch) will keep the truck accelerating in the lower gears up to the rated engine speed.
Caution: LOSS OF VEHICLE CONTROL
To avoid injury from the loss of vehicle control, do not use cruise control under these conditions:
- When it is not possible to keep the vehicle at a constant speed (on winding roads, in heavy traffic, in traffic that varies in speed, etc.).
- On slippery roads (wet pavement, ice-or snow-covered roads, loose gravel, etc.).
Cruise Control will disengage below 1000 rpm or 20 mph (32 kph) road speed. When using Cruise Control, if you want to pull the engine below 1000 rpm, remember to hold the accelerator pedal to the floor to keep the engine pulling at wide-open throttle. The engine will pull down to about 1050 rpm.
Remember: The electronic data programmed into the DDEC system will not allow you to hurt or over fuel the engine at low or lug engine speeds. There is enough oil pressure to withstand hard pulls at low engine speeds.
Cruise Control may also be programmed to permit fast idle using the Cruise Control switches.
With the engine at normal idle, transmission in neutral and service brakes on, press the SPD CNTL Switch, and use the RSM/ACC Switch. The engine rpm should increase to a pre-defined speed. The engine rpm can be raised or lowered from this point using the SET/CST and RSM/ACC switches.