Automatic Transmission/Transaxle: Description and Operation
TRANSMISSIONElectronic Transmission Powerflow Diagram:
Electronic Transmission Component Operation:
The RB4A-EL transmission is a rear wheel drive design with electronically regulated shift activation and lockup torque converter. Operation is controlled by the EC-AT (Electronically Controlled Automatic Transmission) control unit. Operation of engine electronic controls and transmission electronic controls are coordinated to provide greater efficiency.
SELF-DIAGNOSIS FUNCTION
System Description
The self-diagnosis system integrated in the EC-AT control unit diagnoses malfunctions of the main input sensors, the output solenoid valves, and the control unit itself. Malfunctions (both hard faults and intermittents) are stored in control unit memory and can be retrieved as service codes.
General Notes
If there is more than one malfunction, code numbers are displayed in numberical order with 4 second interval between, lowest number first.
The dash hold indicator light flashes indicating the same pattern as the buzzer on the Mazda Self-Diagnosis Checker or DT-S1000 tester. When the data link connector TAT terminal is not grounded (as during normal driving), the indicator flashes at a constant frequency until the malfunction is corrected. At the same time, a service code is stored in the control unit.
The control unit has a built-in fail safe function for the throttle position sensor, vehicle speed sensors, and all solenoids. If a malfunction occurs, the control unit regulates operation of the remaining components according to a preset fail safe program. The vehicle can still be driven, but driving performance may be affected slightly.
Service codes are cancelled when the negative battery cable is disconnected for at least 20 seconds.