TM 5-3805-291-23-1
THEORY OF OPERATION - CONTINUED
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POWERTRAIN - CONTINUED
e.
Safe Mode.
(1)
IBS will enter safe mode if engine speed exceeds 2,550 rpm or torque converter output speed exceeds
3,500 rpm. If IBS enters safe mode, IBS will signal powertrain ECM to upshift transmission speed.
N OT E
IBS is disabled if the left brake pedal is released beyond deadband. After IBS is disabled, the powertrain
ECM controls the transmission shifts according to normal powertrain ECM logic.
(2)
When transmission output speed is less than corresponding safe mode shift point, IBS signals powertrain
ECM to downshift transmission speed. IBS will return to initial or normal mode, dependent upon left
brake pedal position.
f.
Transmission Neutralizer.
(1)
Transmission neutralizer override switch is only input to transmission neutralizer control. Transmission
neutralizer control is enabled when machine is started. Indicator for transmission neutralizer is dark when
control is enabled.
(2)
Transmission neutralizer control is alternately enabled or disabled when momentary transmission neutral-
izer override switch is depressed. Control is disabled if there are any diagnostic codes in left brake pedal
position sensor.
(3)
Transmission neutralizer control uses these inputs: left brake pedal position, engaged transmission speed,
transmission neutralization setpoint, transmission neutralizer control status, and machine ground speed.
(4)
These conditions must be met for transmission to be neutralized:
(a) First speed must be engaged for transmission mode "AUTO 1-4."
(b) Second speed must be engaged for all positions of transmission speed switch except "AUTO 1-4."
(c) Left brake pedal must be depressed beyond transmission neutralization setpoint.
(d) Transmission neutralizer control must be enabled.
(5)
Transmission engages after neutralization if left brake pedal is released and travels at least four degrees
upward from maximum depressed position. Transmission will be neutralized again if left brake pedal is
depressed two degrees from current left pedal position.
(6)
Transmission engages after neutralization if transmission neutralizer control is disabled.
14.
Powertrain Electronic Control Module (ECM).
a.
General. Powertrain ECM is located on cab back wall to right of operator's station. Powertrain ECM shifts trans-
mission. Operator input indicates desired transmission speed and direction. Powertrain ECM makes decisions
based on input and memory information, sending a corresponding response via outputs. Powertrain ECM inputs
and outputs are connected to wiring harness using contact connectors J1 and J2.
b.
Inputs. Machine has inputs from switches and sensors. Switches provide an open, a ground, or a +battery to imple-
ment ECM inputs. Sensors provide a constantly changing signal to powertrain ECM. Inputs into powertrain ECM
are listed in Tables 3 and 4.
c.
Outputs. Powertrain ECM responds to decisions by sending electrical signals via outputs. Outputs can create an
action or provide information to powertrain ECM. Outputs for powertrain ECM are listed in Tables 3 and 4.
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