Electronic Transmission Control Introduction 1-10-03.qxd - GE39

The EH Control System is designed to work in conjunction with the engine electronics for
precise shift control. The TCM receives information on engine RPM, load and throttle position
to provide optimum shift points to maximize fuel economy and driver comfort.
The function of an EGS System is to:
• Monitor all operating conditions through input signals
• Continually assess operating conditions by processing input data and select the
appropriate operating program for current conditions.
• Activate transmission system components and to communicate with other drivetrain
control systems.
• Respond to driver selected driving program (Economy, Sport or Manual).
In addition to providing shift control, the TCM also adapts to changing conditions within the
transmission by monitoring slip ratios and modifying line pressure. This increases the life of
the transmission and reduces maintenance and adjustments. The TCM controls the operation
of the Lock-Up Torque Converter which further increases economy.
On current models, the TCM also has the capability of adapting to driver habits and
responds to changing environmental conditions. Items such as rate of throttle input and
kickdown requests are monitored to select the most appropriate shift program.
The EGS system is also required to maintain occupant safety, safeguard drivetrain damage,
improve vehicle emissions and operate in failsafe mode when a malfunction occurs.
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Electronic Transmission Control