Control Module: Description and Operation

DESCRIPTION
^ The transmission control module (TCM) is incorporated into the power train control module (PCM). The PCM determines the operational characteristics of the Transaxle, such as shift timing or lockup. These characteristics are calculated by a series of switch and sensor inputs to produce optimum drive ability.
^ The PCM has built-in self diagnosis, fail safe, and diagnostic trouble code display functions for the main input sensors and solenoid valves.

SELF DIAGNOSIS FUNCTION
The power rain control module (PCM) has internal self diagnosis functions to warn the driver if a malfunction occurs in any of the main input sensors or output solenoids. If a malfunction occurs, the transmission control indicator lamp (TCIL) (O/D OFF) flashes.

FAIL SAFE FUNCTION
When the self diagnosis function detects a malfunction, the power train control module (PCM) will maintain minimum drive ability through the fail safe system by substituting the signal from a component that is operating correctly for the signal from the failed component. The fail safe function will then continue a normal lockup and shift pattern to maintain minimum drive ability.

TORQUE REDUCTION CONTROL SYSTEM
In order to minimize shift shock, a torque reduction control system is used. This system temporarily reduces engine torque to improve shift quality by cutting off fuel delivery during ups shifts and retarding ignition timing during downshifts. If torque reduction is not possible, the power train control module (PCM) adjusts line pressure to a pre-programmed amount to reduce shift shock.