Adaptive Learning; Outputs From The Tcm; Limp-In Mode Operation; Diagnosis And Service Information - ATSG Chrysler 45RFE Service Manual

ADAPTIVE LEARNING

The 45RFE transmission uses an "Adaptive Learning" feature which allows the TCM to modify the clutch
apply rate to maintain consistant shift quality. This is done based on the amount of wear on the friction elements.
The TCM then adjusts the duty cycle of the shift solenoids to achieve the smoothest possible upshifts and
downshifts. The TCM adjusts the "Clutch Volume Index" when a shift change takes place to optimize clutch to
clutch timing. Clutch Volume Index is described in Figure 6, along with proper clutch volumes and clutch
clearances for the 45RFE transmission.

OUTPUTS FROM THE TCM

Transmission Control Relay - located in the Power Distribution Center (PDC), as shown in Figure 10, and
recieves a ground signal from terminal 15 at the TCM to close the relay. Refer to the wiring schematic in Figure
9.
Underdrive Solenoid with Pressure Switch - This solenoid is normally applied and controls oil to the UD clutch
in all 1st, 2nd, 2nd Prime and 3rd gears of the transmission.
Overdrive Solenoid with Pressure Switch - This solenoid is normally vented and controls oil to the OD clutch in
3rd and 4th gears in the transmission.
Fourth Clutch Solenoid with Pressure Switch - This solenoid is normally vented and controls oil to the 4th
clutch in all 4th and 2nd Prime gears in the transmission.
Second Clutch Solenoid with Pressure Switch - This solenoid is normally vented and controls oil to the 2nd
clutch in all 2nd gears in the transmission.
Low/Reverse Solenoid with Pressure Switch - This solenoid is normally vented and is used to apply the L/R
clutch in 1st from neutral, or coast down to 1st, and to control oil for converter clutch engagement.
Multi-Select Solenoid - The Multi-Select Solenoid is normally applied and controls the OD clutch in 3rd gear
Limp-in, 2nd clutch in Manual 2, 2nd Limp-in and the Low/Reverse clutch in reverse.

LIMP-IN MODE OPERATION

The TCM has the ability to monitor all transmission related electrical components and if it detects a problem,
takes appropriate action, and most of the time results in the TCM setting a Diagnostic Trouble Code (DTC).
Whether this results in MIL illumination, or Limp-in Mode operation, depends on the type of DTC that was set.
If the TCM determines that transmission damage may result from the DTC type that was set, the TCM will shut
off the ground signal to the transmission control relay which will shut off all power to the transmission and the
vehicle will be in Limp-in Mode Operation.
When in Limp-in Mode Operation, with the shift lever in the "Drive" position the transmission will be in 3rd
gear, and if the shift lever is moved to "2" or "L" position the transmission will be in 2nd gear. This will allow the
driver to manually shift the transmission to Limp home.

DIAGNOSIS AND SERVICE INFORMATION

You have been provided with the 23-way case connector pin cavity identification and pin function in Figure 7,
and 60-way TCM connector pin cavity identification and pin function in Figure 8. A complete transmission
wiring schematic is provided in Figure 9, and transmission control relay location in the power distribution center
is shown in Figure 10.
Special tools that might be needed are illustrated in Figure 12, along with the identification of the pressure taps
that are available on the main valve body. Air pressure test passage identification is provided for you in Figure
13.
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