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Copyright © 2009 ATSG
AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
ELECTRONIC COMPONENTS (CONT'D)
Modulated Pressure Control (MPC)
Solenoid Operation
Torque Converter Clutch (TCC)
Solenoid Operation
Shift Solenoid Operation
Shift Pressure Control (SPC)
Solenoid Operation
The Modulated Pressure Control (MPC) Solenoid is
the line pressure control solenoid which controls main
line pressure rise. This solenoid is located in the
electrical conductor plate, uses no "O" ring seals and
relys strictly on the machined surfaces of the solenoid
and the upper valve body to seal the oil pressure. This
solenoid is a Pulse Width Modulated solenoid which
is supplied a variable current flow from the TCM.
When the solenoid is at minimum exhaust, line
pressure is high. When the solenoid is at maximum
exhaust, line pressure is low. The MPC Solenoid is
constantly pulse-width modulating and fluctuates
with throttle movement. Refer to Figure 11.
The MPC and SPC solenoids are interchangeable
and work in tandem together to control holding clutch
pressure as well as to assist the shift solenoids to
control shift feel.
The Torque Converter Clutch (TCC) Solenoid is a
Pulse Width Modulated solenoid that regulates
pressure to the torque converter clutch through the
TCC control valve in the valve body. The TCC
Solenoid is located in the electrical conductor plate,
uses one "O" ring seal and also relys on machined
surfaces of the bottom stem of solenoid and the valve
body to seal the oil pressure. Converter clutch apply
pressure is controlled in order to "ramp" the converter
clutch on and off making for a smooth converter
clutch apply and release. When the solenoid is at
maximum exhaust, the converter clutch is released..
When solenoid is at minimum exhaust, the converter
clutch is fully applied. Refer to Figure 13.
The Shift Pressure Control (SPC) Solenoid regulates
oil pressure to all clutch packs to control the pressure
cutback during a shift, as well as the clamping force
needed to prevent a clutch from slipping. This
solenoid is located in the electrical conductor plate,
uses no "O" ring seals and relys strictly on the
machined surfaces of the solenoid and the upper valve
body to seal the oil pressure. This solenoid is a Pulse
Width Modulated solenoid which is supplied a
variable current flow from the TCM. When the
solenoid is at minimum exhaust, clutch pressure is
high. When the solenoid is at maximum exhaust,
clutch pressure is low. Refer to Figure 12.
The SPC and MPC solenoids are interchangeable
and work in tandem together to control holding clutch
pressure as well as to assist the shift solenoids to
control shift feel.
The 1-2/4-5, 2-3, and 3-4 Shift Solenoids are all
"On/Off", normally closed solenoids. The shift
solenoids are located in the electrical conductor
plate, uses 2 "O" ring seals to seal the oil pressure.
When the solenoid is "ON", it opens and transmits
shift valve command pressure to the corresponding
shift valve. When the solenoid is "OFF", shift valve
command oil pressure is blocked. Refer to Figure
14.
The 1-2/4-5, 2-3, and 3-4 Shift Solenoids are
toggled "On" to make the shift and when the shift is
complete, they are toggled "Off" and remain in the
"Off" state.
The three shift solenoids are also interchangeable.
Electronic Components
Continued on Page 16
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