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.
Table 3.
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.
Detroit Diesel Electronic Controls (DDEC) System
48
All information subject to change without notice.
Copyright © 2014 DETROIT DIESEL CORPORATION
DDC-SVC-MAN-0175