Theory Of Operation; System Components; Required Components - FUNK DF Series Manual

THEORY OF OPERATION

The purpose of the Transmission Control Unit (TCU)
is to control the functions of the transmission.
Upshifting, downshifting, control of the proportional
solenoids and capability to communicate with a panel
mounted gear/diagnostic indicator are the main
functions. The transmission's performance is
determined by the various inputs to the TCU. Based
upon these inputs, the TCU commands the
transmission so that maximum performance can be
achieved under the present operating conditions. All
functions of the TCU are under software control. Park
Brake Solenoid function is connected to the TCU,
however it is not controlled by the TCU or software.
Operation begins when the vehicle's ignition is
switched to the on position, supplying electrical power
to the TCU and related system components from the
vehicle's power source. The TCU now begins
monitoring all inputs and outputs. If a known conflict
in inputs or a fault condition is detected, the TCU will
command the transmission to stay in neutral
regardless of the shift lever position. A flashing error
code will be displayed on the gear/diagnostic
indicator, and will remain displayed until the error has
been resolved and the shift lever cycled back through
the neutral or park position.

SYSTEM COMPONENTS

Required components:

1. Transmission Control Unit (TCU)
2. Engine Speed Magnetic Pickup Sensor (Input
speed)
3. Cylinder Magnetic Pickup Sensor (MPU)
4. Output Speed Magnetic Pickup Sensor (MPU)
5. Shift Lever
6. Temperature Sensor
7. Gear/Diagnostic Indicator
8. Inching Pedal (Optional)
9. Park Pressure
10. Proportional Valves
CTM147 (16JUL98)
Transmission Control Unit
If no error conditions are detected, based upon a
combination of inputs from the shift lever and other
applicable inputs, the TCU will select the proper
transmission gear and command the transmission to
shift to this gear. The gear/diagnostic indicator will
now show the actual transmission gear.
The TCU Module uses electrohydraulic valves to
control the operation of the transmission. The
solenoids controlling the transmission clutches
(solenoids A through D & 1 through 4) are driven by
a signal that produces proportional pressure/flow
changes. During modulation, the solenoids are started
out with a low duty cycle and ramped up to full on.
The initial duty cycle is dependent upon several
factors and is not a preset value. The process of
modulating these clutches greatly enhances shift
quality.
00-105-2
CTM114,105,2 -19-05MAY98
CTM114,105,4 -19-05MAY98
DF Series 150 and 250
160798
PN=209