Sonata V6-3.0L (1991)
Crank Angle And #1 TDC Sensor System
The light emitted from the luminous diodes reaches the photo diodes each time the disc turns. When the photo diodes receive the light transmitted, they
become conductive in the direction opposite to that of ordinary diodes, with the result that current flows as shown by the broken-line arrow in the crank
angle and #1 TDC sensor system image, and approximately 5v is applied to the comparator. When this happens, 5v is transmitted from terminal 1 to the
ECU. Because the light to the photo diodes is interrupted when the slit passes, the current shown by the broken line stops flowing, and terminal 1
becomes O volts. In this way, then, the pulses from the unit assembly are sent to the ECU as signals.
No.1 Cylinder TDC Signal:
Top dead center is detected by the signal obtained from the outer series of slits (1° slits) by reading the 10° blank spot. The ECU, based upon this signal,
determines which of the six pulses from the crank angle sensor is the signal for the No.6 cylinder (referance cylinder), thus synchronizing the ECU with
the rotation of the disc in the distributor. This allows the ECU to determine (with the use of its preset firing order) which pulse is the No.1 cylinder. The
outer circumference slits are also used by the ECU to assist in a more accurate ignition timing at engine speeds below 1200rpm.
Crankshaft Angle Signal:
The six slits located at the inner circumference of the disc serve to detect the position of the crankshaft (and therefore the pistons) relative to top dead
center. The ECU, based on this signal, determines the fuel injection timing, and also calculates the amount of intake-air, the timing of the ignition signal,
etc. for each revolution of the engine.
