1978 Johnson 4HP outboards Service Manual, Page 42Get this manual
POWER PACK OUTPUT TEST aSeparate the three wire connector between the power pack and ignition coilsbInsert jumper between the "C" terminals of both three wire connectorsSee Figure 4-23 cConnect the neon tester blue lead to clean engine ground dConnect jumper wire to the neon tester black lead, and insert the jumper wire to terminal "B" in the power pack end of the connectorSee Figure 4-23eSet the neon tester switch to position number 1fWhile holding load button "A" depressed, crank engine with the starter rope, and observe the light in the neon tester gReverse the jumper wires between terminals "B" andC" in the power pack end of the connectorSee Figure 4-23hWhile holding load button "A" depressedcrank engine with the starter rope and observe the light in the neon testerIf neon light flashes on each output testthe power pack is goodCheck the ignition coilsIf the neon light does not flashor flashes on only one output test, replace the power pack, and repeat the power pack output testPower Pack CD2 can be substituted with known good pack(Be sure power pack ground lead is securely grounded to the powerhead and ohmmeter checks of sensor coil and charge coil have been done first iCheck all wires and terminals for proper location and secure the connectors with retaining clamps