1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 58Get this manual
ROUGH RUNNING ENGINE A rough running engine may be due to interaction of the Power Packs because of faulty isolation diode in Power PacksThe diode may be checked by using an ohmmeter set to high ohms scaleCheck each Power Pack as follows: aDisconnect the leads from Power Pack terminals #6 and #11See Figure 4-18bConnect the ohmmeter leads between the #6 and #11 power pack terminalsNote meter readingcReverse the ohmmeter leads and note readingAn infinite (very high) reading in both directions indicates the diode is openA low ohms reading in both directions (approximately 100 ohms) indicates shorted diodeA normal diode will read resistance in one direction and infinite reading in the other directiondIf diode is defective, replace Power Pack
CHECKING SENSOR COIL
There are six sensor coils potted in the timer baseSee Figure 4-17Four leads from the sensor coils are routed to each Power PackThe port side leads consist of common white on terminal 11, sensor blue lead on terminal 10, sensor green lead on terminal 9, and sensor purple lead on terminal 8See Figure 4-18Port side pack Starboard side pack Connect between power pack terminals and 11 for isolation diode test (rough running engine) Figure 4-18Sensor Leads as Indicated by Broad Arrows