Group 28 Design and Function
Idle Speed Adjustment
Note: This service information should be considered
supplemental to the Engine Control information for base
D12 B and C engine.
The idle speed is adjusted on the VN vehicles at the turn
signal stalk. The idle speed can be adjusted between
500 RPM and 650 RPM.
Prerequisites to adjusting idle speed:
•
Accelerator pedal not depressed.
•
Engine temperature above 45
C (113
F).
•
Vehicle is stationary / Parking brake set.
Idle speed adjustment
1 Cruise control in the ON position.
2 Depress the brake pedal and continue to hold it dur-
ing the entire adjustment procedure.
3 Move the ON/OFF switch to the RESUME position
and hold for four seconds. Release the switch; the
engine speed will drop to approximately 500 RPM.
4 The idle speed can be adjusted with the SET
switch. Each time the SET switch is pressed, the
idle speed will increase approximately 10 RPM.
5 Move the ON/OFF switch to the RESUME position
and the idle speed will decrease approximately 10
RPM each time.
6 Hold in the SET switch and move the ON/OFF
switch to the RESUME position and hold them in
position for four seconds. Release the switches
7 Release the brake pedal and the new idle speed is
set. If an error was made during the adjustment pro-
cedure, the default idle speed will be maintained.
T3014326
1 A-Set
2 B-Resume, On/Off
62
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