The Jeep Grand Cherokee Transmission Control Module

In the past, the various factors
related to influencing the
performance of a vehicle, were
determined by a mechanic,
setting air-fuel mixture ratio,
ignition timing and the idling speed. Control of these factors
was by mechanical and
pneumatic methods. Records
show, that one of the earliest
attempts at using automation
for multiple engine control was performed by BMW in
1939. This could be regarded as
the introduction of the Power-
train Control Module (PCM) and
the Transmission Control
Module (TCM). The Grand Cherokee was
produced by Jeep in 1992, with
the intention of replacing the
Cherokee model. However,
due to the increasing consumer
demand in the "SUV" market segment, the producers elected
to retain both models. The
motoring lifestyle has changed
dramatically since those
experimental times, with cost
effectiveness and driving conditions enforcing
manufacturers continually to
upgrade their production
models. This has created a need
for autonomous inter-relation
between the various engine control units, or modules and
the TCM. The concept of this device,
which is located under the
hood on the driver's side of the
Jeep Grand Cherokee, controls
the entire transmission
electronic operation. It is designed to receive
information related to the
operation of the vehicle, from
direct and indirect sources of
input. Based on this
information, it will determine the operating mode of the
transmission and the correct
shift schedule and points, for
the road conditions prevailing
at the time and the demands of
the driver.