2005 Mercury 50hp 4-stroke - Reverse Polarity

Help. I have a 2005 Mercury 50 hp 4 stroke and have reversed the polarity when hooking up the battery.

I tried to start it with the reversed polarity but only once. Nothing happened so I stopped. No smoking, no fried wires, no electrical burn smells.

I hooked the battery back up correctly and the battery reads approx 12+ volts with my multimeter so I feel confident the battery is still good. However, the motor will not start. The instrument panel/lights works and warning beep sounds. The trim motor works. However, the starter will not spin the motor.

All 4 fuses that I could locate in a single block look good (2-20a, 1-25a & 1-5a). I can bypass the starter solenoid and the start motor spins but the motor will not start so I suspect something in the firing process is screwed also.

Any ideas on where I can start on trouble-shooting this? I'm guessing the solenoid will need to be replaced to at least get the starter motor working again. From there what would you recommend trying next?

Could there be more fuses or fusible links that I'm overlooking than just the four mentioned. Is there any type of resets (like a breaker) I need to check before testing/replacing parts?

Re: 2005 Mercury 50hp 4-stroke - Reverse Polarity

I have the same problem. 2008 Suzuki 40 hp 4 Stroke and I reversed the polarty. I needed to replace the fuse to the marine radio.

Everything works expect the ignition and power tilt are dead. I am no longer hearing a beep when the key is turned on.

Any suggestions?

Re: 2005 Mercury 50hp 4-stroke - Reverse Polarity

There is a fuse at the engine. Here is what it looks like on a 75hp Merc triple. Most engines have a fuse(s) but may not be in the same exact area or look the same. It is the plastic holder with the word "Fuse" by it at the top of the picture.