I have a 71 lb thrust Bow Mount Motorguide trolling motor with a variable speed.  It just recently started to act erradically, ie......the RPM starts to vary at a constant speed.  I took it in to a motor guide dealer and they cant find anything wrong with it.

They told me it was probably something faulty with the boat.  Probably the breaker.  Im pretty sure all that the whole trolling motor wiring consists of the female plug at the bow and the main positive and negative wires that go from the plug to the breaker.  Has anyone experienced this, and how do I test the breaker to see if it is what is malfunctioning.

The breaker looks fine.  It is a waterproof breaker and looks like it is alright.

If it is not the breaker and not the trolling motor itself how could i eliminate components within the system to find what is at fault?

Was the motor off the boat when they checked it? The breaker should either work or not work. It should not cause what is happening. You can bypass the breaker for a short time and that would answer that. If the motor does it again then just bypass the breaker and see if it still does it and as long as the wires are not getting hot you will be OK.

Motor Guides have a problem with the wires within the unit wearing out.

I think it may be time to have your trolling motor serviced.

Also, the gray foot switch on your pedal can give you trouble.  Have it checked out, too.  This is a fact that a Motor Guide rep told my friend and I have had to replace my pedal foot switch.

My Motor Guide died last month and I had Billy Wells in Richmond, the trolling motor expert, look at it. It had burned out the wires in the head and he had to replace one gear.

As for the electrical system, it is very simple and it should not be giving you a problem.  

After checking the fuse and the battery connections there is not much to do.

Consider the investment in having the motor serviced and you should get a lot more years out of it.  

I thought he said he had it check out by a Motor Guide dealer and they said there was nothing wrong with it. Maybe I miss read it.

Yeah, I had it checked out and their tests have come up with nothing abnormal.  I hate this mystery crap.  It could be the switch on the pedal except it is working for the dealer.  Ill bypass the breaker for awhile and try that.  Im just hoping this problem wont end up costing a ton of money.

I was hoping it was a motor issue because it is under warranty.

Just go buy a Minn Kota...problem solved, j/k hook it up straight to battery and see what happens.

If your TM plugs into an outlet in the bow, replace the plug - both the male and female.  Arcing in the plug can make your motor do weird things.