PTT often blowing fuse. What to do?

I have a 2002 115HP 4-Stroke EFI motor. Problem has been happening for 3 years but is getting real bad now. Once in a while when operating the power trim/tilt, it blows the 20A fuse that operates the PTT and the starter. Real pain in the ass when it happens on the water. Used to happen every few times I went out. Now its every time I go out. Sick of changing fuses.

Last year, the relays on the boat went T.U. and I replaced with the newer version retrofit kit that uses relays that look like the ones on a car. Hoped that this would fix the problem, but it didnt.

I traced the green and blue wires for chafe - nothing. Problem happens whether I am using the console buttons or the ones on the side of the motor - happens both ways.

I am wondering if the PTT motor has gone bad and is over-drawing the circuit, but I have no way to test this. Aside from the damned fuse blowing, the PTT seems to work great.

Ideas?

Is the rectifier/regulator working? Sounds like wiring is corroded internally causing increased resistance and current draw then fuse blows. Check each wire completely disconnected w/a digital volt/ohm meter. Each wire should read "0" ohms. Make sure the 12 volt and ground wire connectors are shiny clean and tight.

Buddy of mine had an amp tester. We pulled the green and blue wires that lead to the motor, put them on the tester and ran current through it. Motor current draw spiked as high as 25 and ran steadily at 18-20A. Although I cannot find specs for it, I would assume that the motor should not draw more than 12-15amps when working properly. We tested wiring for resistance also - checked out OK.

Ordered a new motor.

Ordered a new motor.

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Excellent trouble shooting procedure.

My understanding is that before burning out, DC motors sharply increase their amp usage. It seems obvious to me that if a 20A circuit has a component that draws more than 20A, that component must be either mismatched or bad - in either case should be replaced. Is there something wrong with my troubleshooting procedure?

a motor will also draw more current if it is overloaded...such as a bind in a bad bearing or in the driven load...

Sounds like wiring is corroded internally causing increased resistance and current draw then fuse blows.

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If OHM'S law states E=IR than an increase in resistance necessarily results in a decrease in current. No?

a motor is not a pure resistive load..