Dodge Dakota (R1). Manual — part 292
TRANSMISSION CONTROL
MODULE
DESCRIPTION
The Transmission Control Module (TCM) is located
in the engine compartment on the right (passenger)
side and is mounted to the radiator core support (Fig.
12).
OPERATION
The Transmission Control Module (TCM) is the
controlling unit for all electronic operations of the
transmission. The TCM receives information regard-
ing vehicle operation from both direct and indirect
inputs, and selects the operational mode of the trans-
mission. Direct inputs are hardwired to, and used
specifically by the TCM. Indirect inputs originate
from other components/modules, and are shared with
the TCM via the vehicle communication bus.
Some examples of direct inputs to the TCM are:
• Battery (B+) voltage
• Ignition “ON” voltage
• Transmission Control Relay (Switched B+)
• Throttle Position Sensor
• Crankshaft Position Sensor
• Transmission Range Sensor
• Pressure Switches
• Transmission Temperature Sensor
• Input Shaft Speed Sensor
• Output Shaft Speed Sensor
• Line Pressure Sensor
Some examples of indirect inputs to the TCM
are:
• Engine/Body Identification
• Manifold Pressure
• Target Idle
• Torque Reduction Confirmation
• Engine Coolant Temperature
• Ambient/Battery Temperature
• DRBt Scan Tool Communication
Based on the information received from these var-
ious inputs, the TCM determines the appropriate
shift schedule and shift points, depending on the
present operating conditions and driver demand.
This is possible through the control of various direct
and indirect outputs.
Some examples of TCM direct outputs are:
• Transmission Control Relay
• Solenoids
• Torque Reduction Request
Some examples of TCM indirect outputs are:
• Transmission Temperature (to PCM)
• PRNDL Position (to BCM)
In addition to monitoring inputs and controlling
outputs, the TCM has other important responsibili-
ties and functions:
• Storing and maintaining Clutch Volume Indexes
(CVI)
• Storing and selecting appropriate Shift Sched-
ules
• System self-diagnostics
• Diagnostic capabilities (with DRBt scan tool)
NOTE: If the TCM has been replaced, the “Quick
Learn Procedure” must be performed. (Refer to 8 -
ELECTRICAL/ELECTRONIC
CONTROL
MODULES/
TRANSMISSION CONTROL MODULE - STANDARD
PROCEDURE)
BATTERY FEED
A fused, direct battery feed to the TCM is used for
continuous power. This battery voltage is necessary
to retain adaptive learn values in the TCM’s RAM
(Random Access Memory). When the battery (B+) is
disconnected, this memory is lost. When the battery
(B+) is restored, this memory loss is detected by the
TCM and a Diagnostic Trouble Code (DTC) is set.
CLUTCH VOLUME INDEXES (CVI)
An important function of the TCM is to monitor
Clutch Volume Indexes (CVI). CVIs represent the vol-
ume of fluid needed to compress a clutch pack.
The TCM monitors gear ratio changes by monitor-
ing the Input and Output Speed Sensors. The Input,
or Turbine Speed Sensor sends an electrical signal to
the TCM that represents input shaft rpm. The Out-
Fig. 12 Transmission Control Module Location
1 - TRANSMISSION CONTROL MODULE
8E - 18
ELECTRONIC CONTROL MODULES
AN
put Speed Sensor provides the TCM with output
shaft speed information.
By comparing the two inputs, the TCM can deter-
mine transmission gear position. This is important to
the CVI calculation because the TCM determines
CVIs by monitoring how long it takes for a gear
change to occur (Fig. 13).
Gear ratios can be determined by using the DRB
t
Scan Tool and reading the Input/Output Speed Sen-
sor values in the “Monitors” display. Gear ratio can
be obtained by dividing the Input Speed Sensor value
by the Output Speed Sensor value.
For example, if the input shaft is rotating at 1000
rpm and the output shaft is rotating at 500 rpm,
then the TCM can determine that the gear ratio is
2:1. In direct drive (3rd gear), the gear ratio changes
to 1:1. The gear ratio changes as clutches are applied
and released. By monitoring the length of time it
takes for the gear ratio to change following a shift
request, the TCM can determine the volume of fluid
used to apply or release a friction element.
The volume of transmission fluid needed to apply
the friction elements are continuously updated for
adaptive controls. As friction material wears, the vol-
ume of fluid need to apply the element increases.
Certain mechanical problems within the input
clutch assembly (broken return springs, out of posi-
tion snap rings, excessive clutch pack clearance,
improper assembly, etc.) can cause inadequate or out-
of-range element volumes. Also, defective Input/Out-
put Speed Sensors and wiring can cause these
conditions. The following chart identifies the appro-
priate clutch volumes and when they are monitored/
updated:
CLUTCH VOLUMES
Clutch
When Updated
Proper Clutch
Volume
L/R
2-1 or 3-1
downshift
45 to 134
2C
3-2 kickdown
shift
25 to 85
OD
2-3 upshift
30 to 100
4C
3-4 upshift
30 to 85
UD
4-3 kickdown
shift
30 to 100
Fig. 13 Example of CVI Calculation
1 - OUTPUT SPEED SENSOR
2 - OUTPUT SHAFT
3 - CLUTCH PACK
4 - SEPARATOR PLATE
5 - FRICTION DISCS
6 - INPUT SHAFT
7 - INPUT SPEED SENSOR
8 - PISTON AND SEAL
AN
ELECTRONIC CONTROL MODULES
8E - 19
TRANSMISSION CONTROL MODULE (Continued)
SHIFT SCHEDULES
As mentioned earlier, the TCM has programming
that allows it to select a variety of shift schedules.
Shift schedule selection is dependent on the follow-
ing:
• Shift lever position
• Throttle position
• Engine load
• Fluid temperature
• Software level
As driving conditions change, the TCM appropri-
ately adjusts the shift schedule. Refer to the follow-
ing chart to determine the appropriate operation
expected, depending on driving conditions.
Schedule
Condition
Expected Operation
Extreme Cold
Oil temperature below -16° F
-Park, Reverse, Neutral and 1st and
3rd gear only in D position, 2nd
gear only in Manual 2 or L
-No EMCC
Super Cold
Oil temperature between -12° F and
10° F
- Delayed 2-3 upshift
- Delayed 3-4 upshift
- Early 4-3 coastdown shift
- High speed 4-2, 3-2, 2-1 kickdown
shifts are prevented
-Shifts at high throttle openings willl
be early.
- No EMCC
Cold
Oil temperature between 10° F and
36° F
-Shift schedule is the same as
Super Cold except that the 2-3
upshifts are not delayed.
Warm
Oil temperature between 40° F and
80° F
- Normal operation (upshift,
kickdowns, and coastdowns)
- No EMCC
Hot
Oil temperature between 80° F and
240° F
- Normal operation (upshift,
kickdowns, and coastdowns)
- Normal EMCC operation
Overheat
Oil temperature above 240° F or
engine coolant temperature above
244° F
- Delayed 2-3 upshift
- Delayed 3-4 upshift
- 3rd gear FEMCC from 30-48 mph
- 3rd gear PEMCC above 35 mph
- Above 25 mph the torque
converter will not unlock unless the
throttle is closed or if a wide open
throttle 2nd PEMCC to 1 kickdown
is made
8E - 20
ELECTRONIC CONTROL MODULES
AN
TRANSMISSION CONTROL MODULE (Continued)
STANDARD PROCEDURE - TCM QUICK LEARN
The quick learn procedure requires the use of the
DRB
t scan tool.
This program allows the electronic transmission
system to recalibrate itself. This will provide the
proper transmission operation. The quick learn pro-
cedure should be performed if any of the following
procedures are performed:
• Transmission Assembly Replacement
• Transmission Control Module Replacement
• Solenoid Pack Replacement
• Clutch Plate and/or Seal Replacement
• Valve Body Replacement or Recondition
To perform the Quick Learn Procedure, the follow-
ing conditions must be met:
• The brakes must be applied
• The engine speed must be above 500 rpm
• The throttle angle (TPS) must be less than 3
degrees
• The shift lever position must stay in PARK until
prompted to shift to overdrive
• The shift lever position must stay in overdrive
after the Shift to Overdrive prompt until the DRB
t
indicates the procedure is complete
• The calculated oil temperature must be above
60° and below 200°
TRANSFER CASE CONTROL
MODULE
DESCRIPTION
The Transfer Case Control Module (TCCM) (Fig.
14) is a microprocessor-based assembly, controlling
the 4X4 transfer case shift functions via the actua-
tion of a shift motor and utilizing the feedback of a
mode sensor assembly. Communication is via the PCI
serial bus. Inputs include user selectable 4X4 modes
that include AWD(NV244), 2WD(NV233), 4HI, 4LO,
and Neutral. The logic and driver circuitry is con-
tained in a molded plastic housing with an embedded
heat-sink and is located behind the center section of
the lower instrument panel, to the right of the steer-
ing column.
OPERATION
The Transfer Case Control Module (TCCM) utilizes
the input from the transfer case mounted mode sen-
sor, the instrument panel mounted selector switch,
and the following information from the vehicle’s PCI
serial bus to determine if a shift is allowed.
• Engine RPM and Vehicle Speed
• Diagnostic Requests
• Manual Transmission and Brake Applied
• PRNDL
• Ignition Status
• VIN
Once the TCCM determines that a requested shift
is allowed, it actuates the bi-directional shift motor
as necessary to achieve the desired transfer case
operating mode. The TCCM also monitors the mode
sensor while controlling the shift motor to determine
the status of the shift attempt.
Several items can cause the requested shift not to
be completed. If the TCCM has recognized a fault
(DTC) of some variety, it will begin operation in one
of four Functionality Levels. These levels are:
• Level Zero - Normal Operation.
• Level One - Only Mode Shifts Are Allowed.
• Level Two - Only Mode Shifts and Shifts Into
LOW Are Allowed (No Neutral Shifts Are Allowed).
• Level Three - No Shifts Are Allowed
The TCCM can also be operating in one of three
possible power modes. These power modes are:
• Full Power Mode is the normal operational
mode of the module. This mode is achieved by normal
PCI bus traffic being present and the ignition being
in the RUN position.
• Reduced Power Mode will be entered when
the ignition has been powered off. In this state, the
module will shut down power supplied to external
devices, and to electronic interface inputs and out-
puts. From this state the module can enter either
Sleep Mode or Full Power Mode. To enter this mode,
the module must receive an ignition message denot-
ing that the ignition is off, or not receive any mes-
sages for 5 ±0.5 seconds. To exit this mode, the
module must receive one ignition message that
denotes that the ignition is in the RUN position.
Fig. 14 Transfer Case Control Module (TCCM)
1 - TRANSFER CASE CONTROL MODULE
AN
ELECTRONIC CONTROL MODULES
8E - 21
TRANSMISSION CONTROL MODULE (Continued)
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