However, if a transmission is overfilled, a transmis-
sion oil cooler becomes restricted, or if a customer
drives aggressively in low gear, the calculated oil
temperature will be inaccurate. Consequently the
shift schedule selected may be inappropriate for the
current conditions. The key highlights of the vari-
ous shift schedules are as follows:
Extreme Cold: Oil temperature below −16°F
Goes to “Super Cold” schedule when temp rises
above −12°F oil temperature
Park, Reverse, Neutral and 1st and 3rd gear only
No Torque Converter Clutch engagement
Super Cold: Oil temperature between −16°F and
0°F
Goes to “Cold” schedule above 10°F oil tempera-
ture
Delayed 2−3 upshift
Delayed 3−4 upshift
Early 4−3 coastdown shift
Early 3−2 coastdown shift
No 3−1 coastdown or kickdown
High speed 4−2, 3−2, 2−1 kickdown shifts are
prevented
No Torque Converter Clutch engagement
Cold: Oil temperature between 0°F and 36°F
Goes to “Warm” schedule when temp rises above
40°F oil temperature
Shifts at higher throttle openings will be early
High speed 4−2, 3−2, 2−1 kickdown shifts are
prevented
Delayed 3−4 upshift
Early 4−3 coastdown shift
No Torque Converter Clutch engagement
Warm: Oil temperature between 36° F and 80° F
Normal operation (upshifts, kickdowns, and
coastdowns)
No Torque Converter Clutch engagement
Hot (Normal operation): Oil temperature be-
tween 80°F and 240°F
Goes to “Overheat” schedule above 240°F oil
temperature
Reverts to “Warm” when temp falls below 76°F
Normal operation (upshifts, kickdowns, and
coastdowns)
Normal Torque Converter Clutch engagement
operation
Overheat: Oil temperature above 240°F or en-
gine coolant temperature above 244°F
Reverts to “Hot” when temp falls below 230°F oil
temperature or “Super Overheat” above 240°F oil
temperature
Delayed 2−3 upshift (25−32 MPH)
Delayed 3−4 upshift (41−48 MPH)
3rd gear FEMCC from 30−48 MPH
3rd gear PEMCC from 27−31 MPH
A DTC P1738 HIGH TEMPERATURE OPERA-
TION ACTIVATED will be set in the TCM.
Super Overheat: Oil temperature above 260°F
Goes back to “Overheat” below 240°F oil temper-
ature
All “Overheat” shift schedules features apply
2nd gear PEMCC above 22 MPH
Above 22 MPH the torque converter will not
unlock unless the throttle angle is less than 4
degrees (i.e. at 50 MPH a 4th FEMCC to 3rd
FEMCC shift will be made during a part throttle
kickdown or a 4th FEMCC to 2nd PEMCC shift will
be made at wide open throttle) or if a wide open
throttle 2nd PEMCC to 1 kickdown is made.
The TCM requests a Transmission Overheat light
on at 275° Fahrenheit and turns the light off a 265°
Fahrenheit.
Causes for operation in the wrong tempera-
ture shift schedule:
Extreme Cold or Cold shift schedule at start up:
Temperature Sensor or circuitry.
Overheat or Super Overheat shift schedule after
extended operation:
Operation in city traffic or stop and go traffic
Engine idle speed too high − Stuck AIS motor
Aggressive driving in low gear
Long idle time in drive position
Trailer towing in OD gear position (use “3” posi-
tion if frequent shifting occurs)
Cooling system failure causing engine to operate
over 230°F
Engine coolant temperature stays low too long −
If engine coolant temperature drops below 150°F,
the transmission will disengage EMCC. Extended
operation with the EMCC disengaged will cause the
transmission to overheat.
Brake switch or circuitry — The TCM disengages
the TCC when it receives a signal from the PCM
that the brake has been depressed. A problem with
the brake switch or circuitry will cause the EMCC
to disengage. Extended operation with the EMCC
disengaged will cause the transmission to overheat.
Transmission fluid overfilled
Transmission cooler or cooler lines restricted
Engine cooling fan inoperative
Temperature Sensor or circuitry.
3.2.2
LINE PRESSURE CONTROL
Proper control of the transmission line pressure
is essential for proper operation. The 45RFE/
545RFE normally uses closed loop line pressure
control, where actual line pressure (reported by the
line pressure sensor) is continuously monitored.
The TCM determines the desired (target) line pres-
sure which is required and adjusts the Pressure
Control Solenoid until the actual line pressure
matches the desired line pressure value. In the
3
GENERAL INFORMATION