87 17009A5 Ignition Key Switch for Mercury Mariner Outboard Motors Control Box 87-17009A2 Sierra MP41070

Perfect replacement!

I haven't installed this yet, but here's what's wrong. The spring-pressure is very high (spring return from start to run). So that it's hard to operate especially since it has a small key. Second, no rotational locking mechanism was included (bezel,etc.). There is only a very small flat molded into the plastic shaft on the housing. I don't think this will resist the high spring force for long and soon the switch will be rotating in your dash. Skip this one and try another. Two stars to give credit for the correct wire colors.

I recently bought a boat, but the key was long gone. I ordered this after checking the wiring color from the existing ignition. Everything lined up nicely, with the only difference being the wire gauge size. The new switch has slightly smaller gauge wiring, but it all spliced up nicely. I got it all back together, and so far so good. I need to get a new battery to fully test, but dry run of key switching to different positions went smoothly. Since all the colors on the wires matched up, I am pretty confident in it as the rest of the switch is ruggedly built. Will update with any problems, should I run into any.

I picked this up as I am going through the electrical on my old JD tractor. The ignition was bypassed when I bought it. This fit in the existing hole with no issues. Wiring was pretty straight forward with the exception that the wiring is very small, so I utilized 2 relays to not melt the switch. One relay to trigger key on and a second for the starter circuit. This is a great retrofit key for anything that is subjected to weather.