Maximum Engine Speed Sensor

ECU senses engine speed based on impulses from "TD" terminal of ignition switching unit. Interpreting this information, ECU governs engine speed by changing electrical current to Electro-Hydraulic Actuator (EHA), which in turn controls differential pressure regulator. Increasing lower chamber pressure to system pressure interrupts fuel supply to injection valves. This causes a leaner mixture.

Fuel pump relay also receives maximum engine RPM signal. At maximum RPM, signal interrupts contact between circuits No. 30 and 87 and shuts off fuel pump.