GEAR RATIOS
The 545RFE gear ratios are:
OPERATION
The 45RFE/545RFE offers full electronic control of all automatic up and downshifts, and features real-time adaptive
closed-loop shift and pressure control. Electronic shift and torque converter clutch controls help protect the trans-
mission from damage due to high temperatures, which can occur under severeoperating conditions. By altering shift
schedules, line pressure, and converter clutch control, these controls reduce heat generation and increase trans-
mission cooling.
To help reduce efficiency-robbing parasitic losses, the transmissions includes a dual-stage transmission fluid pump
with electronic output pressure control. Under most driving conditions,pump output capacity greatly exceeds that
which is needed to keep the clutches applied. The 45RFE/545RFE pump-pressure control system monitors input
torque and adjusts the pump pressure accordingly. The primary stage of thepump works continuously; the second
stage is bypassed when demand is low. The control system also monitors input and output speed and, if incipient
clutch slip is observed, the pressure control solenoid duty cycle is varied, increasing pressure in proportion to
demand.
A high-travel torque converter damper assembly allows earlier torque converter clutch engagement to reduce slip-
page. Needle-type thrust bearings reduce internal friction. The 45RFE/545RFE is packaged in a one-piece die-cast
aluminum case. To reduce NVH, the case has high lateral, vertical and torsional stiffness. It is also designed to
maximize the benefit of the structural dust cover that connects the bottomof the bell housing to the engine bed-
plate, enhancing overall power train stiffness. Dual filters protect thepump and other components. A cooler return
filter is added to the customary main sump filter. Independent lubrication and cooler circuits assure ample pressure
for normal transmission operation even if the cooler is obstructed or the fluid cannot flow due to extremely low
temperatures.
The hydraulic control system design (without electronic assist) provides the transmission with PARK, REVERSE,
NEUTRAL, SECOND, and THIRD gears, based solely on driver shift lever selection. This design allows the vehicle
to be driven (in “limp-in” mode) in the event of a electronic control systemfailure, or a situation that the Transmis-
sion Control Module (TCM) recognizes as potentially damaging to the transmission.
The TCM also performs certain self-diagnostic functions and provides comprehensive information (sensor data,
DTC’s, etc.) which is helpful in proper diagnosis and repair. This information can be viewed with the DRB
scan
tool.
DIAGNOSIS AND TESTING
AUTOMATIC TRANSMISSION
CAUTION: Before attempting any repair on a RFE automatic transmission, check for Diagnostic Trouble
Codes with the scan tool.
Transmission malfunctions may be caused by these general conditions:
Poor engine performance
