Interface to Petrol Engine Control Module (ECM) (Z132)

The Auto Gear Box Control Unit (Z255) takes the engine torque, engine speed and throttle angle signals from the ECM, calculates which gear is required, outputs to the solenoid valves and sends a torque reduction signal back to the ECM, thereby retarding the ignition point on each of the cylinders and so giving a reduction in engine power during gear changes that result in a smooth change.

Petrol:
Information about engine speed, engine torque, throttle angle and torque reduction is received from the Engine Control Module (Z132) by the Auto Gear Box Control Unit (Z255) via its CAN bus 'high' and 'low' line on pins 16 and 44.