1985 OMC 65, 100 and 155 HP Models Commercial Service Manual, PN 507450-D, Page 168Get this manual
The second magnetic pole of the sensor magnet travels another 900 to sensor coil No.3 producing the signal to turn on S.CRNo.3 back in the first power packCurrent leaves the sensor coil through wire (b) which is positive (+) and enters the power packCurrent flows to the No.3 S.C .Rgate turning on S.C.R and returns to the common side of the sensor coilThe first magnetic pole travels 90 passing sensor coil No.4, applying positive signal to the gate of S.CRNo4 in the sec ond power packCurrent leaves the sensor coil through wire (a) which is positive and enters the power packCurrent flows to the No.4 S.CRgate turning on S.C RNo.4 and returns to the common side of the sensor coilThis all takes place in one revolution of the engine and then the sequence begins allover again for the next revolution :