1978 Johnson 175, 200, 235 HP Outboard Service Manual, Page 56Get this manual
Figure 4-16BSensor Coil Checks (2) If meter reads lower than 0.3 on any sensor, check for shorts to groundAlso check sensor resistanceIf sensor resistance meets specifications, low meter reading is caused by low engine rpm or weak sensor magnets in flywheelSensor Coil (Short to Ground Test) aRemove sensor leads from power pack terminals #8#9, #10 and #11bConnect meter black lead to timer base and red meter lead to one sensor lead, see Figure 4-16BCrank engine and observe meter readingConnect meter red lead to other sensor lead: Crank engine and observ,e meter readingConnect meter red lead to other sensor lead: Crank engine and observe meter reading: Connect meter red lead to remaining sensor lead: rank engine and observe meter reading(1) If meter reads zero during all checks, sensor is okay, go to Step 5(2) If there is any meter reading above zero, sensors are groundedRepair or replace timer base