AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
7
Copyright © 1999 ATSG
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.
UnderdriveSolenoid withPressureSwitch- Thissolenoid isnormally appliedand controlsoil tothe UDclutch
inall 1st,2nd,2ndPrimeand3rdgearsofthetransmission.
OverdriveSolenoidwithPressureSwitch-Thissolenoidisnormallyventedandcontrolsoilto theOD clutchin
3rdand 4thgears inthetransmission.
Fourth Clutch Solenoid with Pressure Switch - This solenoid is normally vented and controls oil to the 4th
clutchin all4th and2ndPrimegearsinthetransmission.
Second Clutch Solenoid with Pressure Switch - This solenoid is normally vented and controls oil to the 2nd
clutchin all2nd gearsinthetransmission.
Low/Reverse Solenoid with Pressure Switch - This solenoid is normally vented and is used to apply the L/R
clutchin 1stfromneutral,orcoastdownto1st,andtocontroloilforconverterclutchengagement.
Multi-Select Solenoid - The Multi-Select Solenoid is normally applied and controls the OD clutch in 3rd gear
Limp-in,2nd clutchinManual2,2ndLimp-inandtheLow/Reverseclutchinreverse.
LIMP-IN MODE OPERATION
DIAGNOSIS AND SERVICE INFORMATION
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).
Whetherthis resultsinMILillumination,orLimp-inModeoperation,dependsonthetypeofDTCthatwasset.
IftheTCMdeterminesthat transmission damage may resultfromtheDTC type that was set,theTCMwillshut
off the ground signal to the transmission control relay which will shut off all power to the transmission and the
vehiclewill bein Limp-inModeOperation.
When in Limp-in Mode Operation, with the shift lever in the "Drive" position the transmission will be in 3rd
gear,andif theshift leverismoved to"2"or "L"positionthetransmissionwill bein2nd gear. Thiswillallow the
driverto manuallyshiftthetransmissiontoLimphome.
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
wiringschematicisprovidedinFigure9, andtransmission controlrelaylocationinthepowerdistribution center
isshown inFigure 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.
ADAPTIVE LEARNING
The 45RFE transmission uses an "Adaptive Learning" feature which allows the TCM to modify the clutch
applyratetomaintainconsistantshiftquality. Thisisdone basedon theamountofwearonthefriction 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
clearancesfor the45RFE transmission.
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