3315766 - E7050 AUTOMATIC TRANSMISSION - Functional description
Functional description
The electronic automatic transmission (EAT) control unit M55 monitors and governs the entire automatic transmission management system. The control unit direct supply reaches pin 55 of M55 via the line protected by fuse F10 of junction unit B2. The ignition-operated supply (15/54) from the line for relay T17 of engine compartment junction unit B1 and protected by fuse F9 in B1, reaches pins 31 and 54 of M55. Pins 6, 28 and 34 of control unit M55 are earthed C61 .Control unit M55 is connected to CAE solenoid L50, which contains the valves which control the pressure regulators and certain sensors:
- pin 52 of M55 supplies the solenoids, whose control signals are sent from pins 30 and 33 of M55;
- pin 3 of M55 supplies the pressure regulators, whose control signals are sent from pins 1, 4, 5 and 29 of M55 ;
- pins 14, 42 and 23 of M55 are connected to the car speed sensor inside unit L50;
- pins 16, 44 and 15 of M55 are connected to the transmission input rpm sensor inside unit L50;
- pins 21 and 22 of M55 are connected to the oil temperature sensor inside unit L50;
Control unit M55 is connected to the EAT sensor unit via junction D79:
- pin E of D79 is supplied via the line protected by fuse F10 of junction unit B2: pin K is earthed C61.
- pins G and H of D79 are connected to the reversing sensor and send signals to turn on the reversing light See E2022 REVERSING LIGHTS
- pins A, B, C and D of D79 are connected to control unit M55 and indicate the positions assumed by the lever selector to pins, 36, 8, 37 and 9 of M55 respectively.
Control unit M55 governs a series of safety checks:
- shift lock (lever locked if key not turned to MAR and brake pressed): sends a signal from pin 32 to the speed control unit H37 pin 14;
- key lock (key locked if the gear selector is not set to P): sends a signal from pin 49 to relay J6 ; the battery-operated signal runs along the line protected by fuse F5 of junction unit B1. and controls the lock solenoid built into igntion switch H1 (connettore B).
- door open buzzer; the signal that the driver's door is open - lock N50 reaches pin 45 of M55 ; the command for the buzzer, located in gear control unit H37 pin 11, is sent from pin 51
- start-up (the engine will start only with the gear shift set to P or N): a signal is sent from one of the two sensors (pin I of connector D79 to the relayT20 of B1 which supplies the starter motor A20 coil (pin 50). The starter motor coil power circuit is protected by fuse F3 of B1 [ E5010].