1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 59Get this manual
dIn some conditions, sensors may be grounding out to the shield but will not show up with an ohmmeterThis condition may be found by using the condenser tester leakage test, where voltage of approximately 500 volts is applied to the sensorSee Figure 4-21 IgiuiJI NOTE
Disconnect all sensor leads from Power Pack
1White lead Figure 4-19Checking Starboard Side Sensor Coils purple lead leaving the meter black lead cOimected to the common white leadSee Figure 4-19bWith sensor leads still disconnected from Power Pack, connect ohmmeter (HI ohms scale) alternately between each sensor lead and groundInfinity reading on each sensor indicates good sensorZero or any reading indicates leads or sensor coil is shorted to groundSee Figure 4-20 &63580
Meter red lead Meter Meter black lead Timer base and sensor coil assembly Starboard sensor leads Port side sensor leads
Figure 4-21Testing Sensors for Grounded Condition eGround the black lead of the tester to the timer base assemblyAttach the red lead of the tester to one of the sensor leads, and apply the leakage testRepeat test on each sensor leadMeter will indicate if shorting(Be sure sensor leads are not touching each other or touching ground