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Help with starting after replacing shift sw. Johnson 50ESL72C

J

jbreed

New member
With help from this forum we were able to diagnose the problem with the motor stuck in neutral, the shift sw. as bad. new sw. was a 3 or 5 wire set up & supposed to come with wiring diagram but did not. This was not a problem as all wires were color coded.

However, after replacing the sw. the motor will not start. Doing tests on the terminal block indicates there is no power to the coils. We do not understand how replacing the sw could affect starting, the motor has always started great.

We put the old sw back in as it started fine with it, but now same result.

We're stumped, looking for any ideas.
 
Does it try to turn over or is it just dead?

The problem may or may not be associated with the shift switch replacement. Try not to make assumptions. Test everything to find the problem.

Check your PMs.
Bill
 
Are you saying that you still have the "old" shift switch installed and the engine won't start, fire, run.... or are you saying that the electric starter will not crank the engine over?

That engine requires a specific "Hydro Electric Shift" type shift switch... You cannot use the older type straight "Electric Shift" switch.

If you truly managed to find a Hydro Electric Shift switch, it would have 5 terminals. What are those terminals marked? Also, what color are the wires that attach to it?
 
If I am correct in my assumption the shift diode contains two diodes (Full Wave Rectifier) and rectifies the AC from the charging circuit as the engine winds down after being shut off. This prevents the gearcase from shifting into Forward when you shut the engine off with the ignition switch until the engine winds down.

The shift diodes should conduct in one direction and show Infinity (an Open) in the other direction. A multimeter with a Diode check function is the best tool to check them. A regular multimeter can be used if it provides enough voltage to bias (turn on) the diodes (.7vdc).

Bill
Full Wave Rectifier

diode18.gif
 
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The motor turns over no spark. I got the same Hydro sw, which does not have terminal but wires coming directly out of the sw. It has 2 white, 1 blue, 1 green & 1 purple. The old sw. had the purple, green & blue connected to same color wire in control with both white not connected to anything which is exactly how we connected the new one. When it would not start with the new sw. we put the old one back in just to see of it made any difference which it did not.
 
The white wires are the start-in-neutral-only safety switch part of the shift switch. You have disabled the function by not wiring it correctly.

Nevertheless, that has nothing to do with the no spark condition. Completely different circuits.
 
Purple wire = 12v source, should be connected to the "A" (acessory) terminal of the ignition switch.

Green wire = Neutral, should be connected to the Green wire that leads to the lower unit.

Blue wire = Reverse (when used in conjunction with the Green wire), should be connected to the Blue wire leading to the lower unit.

White wire = Doesn't matter which one... should be connected to the "S" (solenoid) terminal of the ignition switch.

White wire = The remaining white wire... should be connected to one of the 3/8" nuts of the starter solenoid.
 
Thanks joereeves. I'll double check that we have it wired correctly. fdrgator comments that the white wires are only for the start in neutral part of the shift sw, so I'm wondering what purpose the one white wire to the starter solenoid serves?
and am I correct that there's nothing in the shift sw wiring that would cause no power to the coils resulting in no spark?
just seems odd that I've never had a start problem until I replaced this sw. and do not see the connection between the two.
 
jbreed said:
I'm wondering what purpose the one white wire to the starter solenoid serves?
Click to expand...

When the key is in the START position and the shift switch is in neutral, 12v is applied to the "S" terminal of the ignition switch (white wire) which is transfered to the shift switch. Within the shift switch, that 12v is applied to the other remaining white wire which leads to the engagement 3/8" nut of the starter solenoid. The 12v is now applied to the inner windings of the starter solenoid which is connected to the remaining 3/8" nut of the solenoid that has a black wire connected to a power head ground.

This completes the circuit and the starter solenoid should engage causing the electric starter to crank the engine over.

The shift switch has nothing to do with the ignition.
 
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