Stern thruster runs spontaneously!

[trialframe]

We were in our Nimbus 340 moored in the marina when the stern thruster suddenly started running. It took me a few moments to realise what was happening and then I was able to stop it by switching off the 'side power' switch on the panel. Now when I switch this back on usually the stern thruster runs spontaneously - but sometimes it doesn't. This is leading me to think that there is a fault in a control box somewhere because the switch that tells the thruster to go right or left only has thin wires supplying it. Presumably these thin wires go to a control box where there may be a solenoid or similar high current switch which actuates the thruster motor right & left.
It is a Sleipner stern thruster. I need to know where to look for the offending control box because it is very difficult to trace the thin wires away from the control switch. Might the control box be built into the actual thruster or would it possibly be a separate part mounted near the stern thruster fuse? Any help with this would be gratefully accepted.
By the way the switch that actuates the thruster to go right or left is a conventional one and not a touch panel so it is unlikely to be faulty.

 

[reginaldon]

The old Thames Sailing barge skippers never had that problem!

 

[Gordonmc]

Nostrodamus if this parish had a similar problem with his bow thruster.
A search of his threads may turn up how he resolved the problem.

 

[Marsupial]

your problem is caused by condensation in the control box by the helm - sorry but you will probably need a new one.

There are two relays on the motor, one for left one for right, they in turn are controlled by a "black box" its fitted in a recess below the relays the control box plugs into it. The black box prevents you from selecting left-right quickly so you don't break the gearbox. You can check with side power that you have the latest release of the software in the black box component.

That said, the controller by the helm is the bit that gives the trouble you describe in my experience.