Electrical Operation; Inputs To The Tcm - ATSG Chrysler 45RFE Service Manual

ELECTRICAL OPERATION

The Transmission Control Module (TCM) controls all of the transmission functions and is located in the engine
compartment, as shown in Figure 5. The Powertrain Control Module (PCM) does not control the transmission.
The electronic components of the 45RFE transmission consist of various sensors and switches as input
information to the TCM, that the TCM uses to determine the appropriate gear ratio and shift schedule points.
There is also the associated wiring, fuses, relays, connectors, splices and grounds for the transmission to
function as designed. A complete transmission wiring schematic has been provided for you in Figure 9.
The final output from the TCM is to the six shift solenoids and the line pressure control solenoid located in the
Solenoid Pack/Transmission Range Sensor assembly and bolted on the valve body as shown in Figure 4. The
solenoids in this transmission are unique in that some are normally vented and some are normally applied and is
illustrated in Figure 4. The TCM also communicates with other control modules, such as the PCM, currently
using the two wire CCD Bus for communication. The TCM recieves power from two sources, fused battery
power to pin 56 and fused ignition switch input to pin 11, both at the 60-way connector on the TCM. The TCM
also has a ground to complete its electrical circuit. (See Figure 8).

INPUTS TO THE TCM

Input and Output Shaft Speed Sensors - are located on the left side of the transmission and are illustrated in
Figure 11. The input shaft speed sensor reads input shaft speed off of a tone wheel. The TCM compares this
reading with that of the output shaft speed sensor, which is also read off of a tone wheel. This comparison
provides the TCM with gear ratio information. The crankshaft position sensor supplies the TCM with engine
RPM data that is also critical to scheduling shift points.
Line Pressure Sensor - is located on the right rear of the transmission, as illustrated in Figure 11, and supplies
the TCM with line pressure information. The line pressure sensor operates much like a throttle position sensor.
Transmission Fluid Temperature Sensor - is located in the Solenoid Pack/Transmission Range Sensor and is a
thermister that the TCM uses to moniter transmission fluid temperature.
Overdrive Cancel Switch - located on the shift lever and cancels overdrive operation.
Solenoid Pack/Transmission Range Sensor - contains several different inputs to the TCM. The TRS contains
five switches that tell the TCM, through different combinations of switch states, what position the manual gear
selector has been placed. There is also a back-up lamp switch incorporated in the TRS.
In addition to the switches above, there are five pressure switches to moniter pressure in the Low/Rev, Second
Clutch, Fourth Clutch, Underdrive Clutch and Overdrive Clutch hydraulic circuits. The primary function of
these switches is to help the TCM detect when clutch circuit hydraulic failures occur. The TCM continuously
monitors the switches for the correct states (Open or Closed) in each gear as shown in the chart in Figure 5.
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