TM 5-3805-291-23-1
THEORY OF OPERATION - CONTINUED
0003 00
POWERTRAIN - CONTINUED
b.
IBS uses these inputs to downshift transmission:
"Integrated Braking System Manual Mo e Enable Status" in powertrain ECM
d
Left brake pedal position
Autoshift switch position
Actual transmission speed
Calibrated initial brake pressure point
Torque converter output speed
Transmission output speed
Engine speed
c.
IBS is enabled if these conditions are met:
"Integrated Braking System Manual Mo e Enable Status" is set to "Enable"
d
Left brake pedal position sensor has been calibrated
Engine speed is below 2,425 rpm
Left brake pedal is depressedbeyond left brake pedal deadband
Torque converter output speed sensor, transmission output speed sensors, and left brake pedal
position sensors do not show any diagnostic codes
d.
Initial Mode and Normal Mode.
(1)
IBS is in initial mode when operator depresses left brake pedal between deadband and calibrated initial
brake pressure point. IBS is in normal mode when operator depresses left brake pedal between calibrated
initial brake pressure point and point of maximum pedal travel.
(2)
IBS performs these functions when operator depresses left brake pedal in initial or normal mode:
(a) If transmission is in third or fourth speed, transmission will downshift one speed at a time until second
speed is reached. Transmission will downshift regardless of autoshift switch position. Each downshift
will occur when transmission output speed decreases to shift point for current transmission speed.
(b) Transmission will downshift from second to first speed if autoshift switch is in "AUTO 1-4" position.
Transmission will downshift when transmission output speed decreases to "2-1" shift point for initial
or normal mode.
(c) If autoshift switch is not in "AUTO 1-4" position, transmission will not downshift from second to first
speed unless operator depresses transmission downshift switch. Operator may need to depress switch
twice. Machine ground speed determines if transmission downshift switch is depressed once or twice.
(Depress switch once if ground speed is below "AUTO 2-1" speed, and twice if ground speed is above
"AUTO 2-1" speed.)
(3)
After operator releases left brake pedal and pedal returns beyond deadband, these events occur:
(a) If autoshift switch is in MANUAL position, IBS shuts off. Powertrain ECM upshifts transmission
sequentially to speed selected by transmission direction and speed control.
(b) If autoshift switch is in any "AUTO" position, IBS shuts off. Transmission resumes automatic control
of speed shifts.
0003 00-30
