Mack V-MAC IV, Operator'S Handbook Manual

Page: 72 / 133

64 V-MAC Co-Pilot Operator's Manual
Low Idle Adjustment
Note: On chassis equipped with an automatic transmission, the speed control
switches cannot be used to adjust engine low idle speed. Attempting to set low idle
in this manner will cause the vehicle electronic control unit (VECU) to enter the
reprogramming mode resulting in the idle speed dropping to 550 RPM (650 RPM for
non-catalyzed exhaust aftertreatment system), but it will not be possible to set a new
idle speed. If the reprogramming mode is entered, simply turn the speed control switch
OFF, and idle speed will return to the originally set speed. Resetting low idle speed on
a chassis equipped with an automatic transmission requires a scan tool running the
VCADS software. Consult the
VCADS User's Guide for additional information.
This section explains the procedure to reset the low idle speed using the Speed
Control switches.
The vehicle management and control (V-MAC) IV system allows the low idle to be
set within the range of 550 to 700 RPM (650–700 RPM for non-catalyzed exhaust
aftertreatment system). This provides flexibility to set the low idle to the smoothest
engine speed for the vehicle.
There are two steps required to reset the low idle speed. The first step places the
vehicle management and control (V-MAC) IV system into the low-idle adjust mode.
In this mode, vehicle management and control (V-MAC) IV is ready to accept the
new idle speed.
The second step is to actually tell vehicle management and control (V-MAC) IV
what the new idle speed will be.
The first phase in the process is meeting the requirements listed below.
1 The vehicle management and control (V-MAC) IV system must have the Low-Idle
Adjust option enabled in the customer data space. This function can be disabled
by the customer.
2 Be sure there are no active faults in the system.
3 The vehicle must be stationary.
4 The parking brake must be applied.
5 The accelerator pedal (AP) must be at the idle position (not pressed).
6 The Speed Control ON/OFF switch must be turned ON and OFF 3 times within
two seconds. At this point, the idle speed will drop to 550 RPM, and vehicle
management and control (V-MAC) IV will now be ready to accept a new speed.
Be sure to leave the ignition key in the ON position.
https://truckmanualshub.com/