trol circuit. The Brake/Transmission Shift Interlock
(BTSI) solenoid and the park lockout solenoid (also
part of the SLSA) are controlled by the TCM.
The PCM and ABS broadcast messages over the
controller area network (CAN C) bus for use by the
TCM. The TCM uses this information, with other
inputs, to determine the transmission operating con-
ditions.
The TCM:
• determines the momentary operating conditions
of the vehicle.
• controls all shift processes.
• considers shift comfort and the driving situation.
The TCM controls the solenoid valves for modulat-
ing shift pressures and gear changes. Relative to the
torque being transmitted, the required pressures are
calculated from load conditions, engine rpm, vehicle
speed, and ATF temperature.
The following functions are contained in the TCM:
• Shift Program
• Downshift Safety
• Engine Management Intervention
• Torque Converter Lock-Up Clutch.
• Adaptation.
This transmission does not have a TCM relay.
Power is supplied to the Shift module and the TCM
directly from the ignition.
The TCM continuously checks for electrical prob-
lems, mechanical problems, and some hydraulic prob-
lems. When a problem is sensed, the TCM stores a
diagnostic trouble code (DTC). Some of these codes
cause the transmission to go into 9Limp-In9 or
9default9 mode. Some faults cause permanent
Limp-In and others cause temporary Limp-In. The
W5J400 defaults in the current gear position if a
DTC is detected, then after a key cycle the transmis-
sion will go into Limp-in, which is mechanical 2nd
gear. Some DTCs may allow the transmission to
resume normal operation (recover) if the detected
problem goes away. A permanent Limp-In DTC will
recover when the key is cycled, but if the same DTC
is detected for three key cycles the system will not
recover and the DTC must be cleared from the TCM
with the DRBIIIt scan tool.
TCM SIGNALS
The TCM registers one part of the input signals by
direct inputs, the other part by CAN C bus. In addi-
tion to the direct control of the actuators, the TCM
sends various output signals by CAN C bus to other
control modules.
Selector Lever Position
A series of 12 Hall-effect switches in the SLSA
inform the TCM of the position of the selector lever.
The TCM monitors the SLSA for all shift lever
positions through five position circuits. The SLSA
provides a low-current 12-volt signal to the TCM.
The TCM compares the on/off signals to programmed
combinations to determine the exact position of the
shift lever.
ATF Temperature Sensor
The ATF temperature sensor is a PTC thermistor.
It measures the temperature of the transmission
fluid and is an input signal for the TCM. The tem-
perature of the ATF has an influence on the shift
time and resulting shift quality. As the temperature
rises, resistance rises. Therefore the probing voltage
is decreasing. Because of its registration, the shifting
process can be optimized in all temperature ranges.
The ATF temperature sensor is connected in series
with the park/neutral contact. The temperature sig-
nal is transmitted to the TCM only when the reed
contact of the park/neutral contact is closed because
the TCM only reads ATF temperature while in a for-
ward gear.
Starter Interlock
The TCM monitors a contact switch wired in series
with the transmission temperature sensor to deter-
mine PARK and NEUTRAL positions. The contact
switch is open in PARK and NEUTRAL. The TCM
senses transmission temperature as high (switch
supply voltage), confirming switch status as open.
The TCM then broadcasts a message over CAN bus
Fig. 3 Shifter Assembly and Transmission Control
Module
1 - SHIFTER ASSEMBLY
2 - TRANSMISSION CONTROL MODULE
WG ELECTRONIC CONTROL MODULES 8Ea - 5
TRANSMISSION CONTROL MODULE (Continued)
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