Logo

1996 90 hp Merc faulty switchbox

lucasvdv

New member
Dear Marine Engine Forum users,

I am new here, so I hope this is posted in the correct section.

I have an 1996 90hp Mercury Outboard with serial number 0G279670. Last week I had some problems with my outboard. It runs rough, starts difficult and seems to sputter when accelerating. This al happend on holiday and had to bring it in to a mercury mechanic. This mechanic only had limited amount of time to fix the issue due to me leaving the country again. In this limited time he diagnosed the problem to be in the switch box. As a work around he sort of solved the problem by disconnecting the black/yellow wire from the switchbox and the motor would run fine. Start right up, accelerates fine, everything normal. The mechanic advised me that when I got home I should replace this switchbox, because the problem is within this device. And without the black/yellow wire connected to the switchbox, my safety lanyard is not working and I could only turn of the engine by pressing the black/yellow wire to an engine ground.

I trust this mechanic, but I started thinking how I could be possilbe that the engine runs fine when the black/yellow wire is not connected and with this wire connected it runs really rough or not at all. To check this for myself, I have tested the other end of this black/yellow wire running through the remote control module, the ignition switch and safety lanyard switch. This wiring seems to be fine. With the ignition switch in the off position, there is continuity with ground. When I put the ignition switch in the on position, there is no longer continuity with ground. On the other hand when I pull the lanyard, continuity with ground is achieved. So in my opinion, this works as it should be.

Can anyone explain to me how this behavior is possible? If the outcome is that I should replace the switchbox, i am fine with that. But I also would like to know the reason why I could run fine without the black/yellow kill wire connected to it if the problem is inside the switchbox.

I apologize for the long story, but I hope this is useful.

Thanks in advance.
 
The switch box is fine, the circuit going to it is bad. IT probably shorts out as the wiring (or ??) is giggled.

Jeff
 
Last edited:
Back
Top