Transmission Control Systems: Description and Operation

A/T Control System Diagram:

Wiring Diagram (Part 1 Of 2):

5eG'Wiring Diagram (Part 2 Of 2):

DESCRIPTION
The RE4R03A is a fully automatic four-speed electronically controlled transmission. It senses vehicle operating conditions through various sensors. Also, it controls the optimum shift position and reduces shifting and lock-up shocks.

FAIL SAFE DESCRIPTION
The Automatic Transmission Control Unit has an electronic Fail-Safe (limp home mode) to allow the vehicle to be driven even in the event of damage of a major electrical input or output device circuit.

FAIL SAFE OPERATION
In this condition, the vehicle runs in third gear in positions 1, 2 or D and will not upshift. Customer may say "Sluggish, poor acceleration".
When Fail-Safe operation occurs the next time the key is turned to the ON position, the diagnostic information display will display "Transmission malfunction".
If the vehicle is driven under extreme conditions such as excessive wheel spining and emergency braking suddenly after, Fail-Safe may be activated even if all electrical circuits are undamaged. In this case, normal shift pattern can be returned by turning key OFF for 3 seconds and then back ON.
The indication by the diagnostic information display will appear only once and be cleared. The customer may resume normal driving conditions by chance.
The Self-Diagnosis will indicate the damage of the vehicle speed sensor or the revolution sensor.
During the next Self-Diagnosis performed after checking the sensor, no damages will be indicated.