Thread: So Many wires..

I am writing this so if anyone needs to replace a Mercury switch they can avoid my stupidity.

My starter switch was acting up. It would take a few turns at times for it to catch. Therefore I decided to replace it before it stopped working totally. I ordered one before I pulled out the original switch so I did not know how the connections were made.

On Overtons there were two swtiches with the push choke for a Mercury motor. One was advertised as a "control box" (embedded wires)




and the other as "panel mount" (exposed connectors).

I bought the panel mount because the existing switch was mounted with a small panel on the side rail area.

I got home from work on Wednesday (July 3) and the switch was in the mail. I figure it should only take under an hour to install so I start pulling things apart. I do NOT unhook the starting battery. I unscrew the panel and pull out the switch. First thing I notice it that the original switch is actually what was advertised as the "control box" one. No big deal. I had crimping ring terminals to use on the wires which would connect to the exposed tabs with the included bolts.

There are 6 wires. Black, red, purple, white w. red stripe, black w. yellow stripe, and yellow w. black stripe. Since the existing switch was all imbedded in a solid material I had no real reference to what each wire was used for. Red and black are obviously positive and negative and I hook them up ( I was correct). The attachment is the wiring diagram for the new switch.

Attachment 130282

The other 4 I have absolutely no clue on. I do some research and find charts about the general colors used on Mercury systems. So I decide that Purple is choke, R/W is the starter, Y/B is the Magneto and B/Y is left so i must be the Solenoid. I put in the key and turn it to the first spot and the motor tries to start. So I am wrong. I do some more research and start swapping wires. I unscrew the choke bolt and it falls and hits the positive and negative terminals and I see a spark and just know I blew a fuse. So I finish moving the wires around and turn the key and push the key and nothing confirming my fuse theory.

I get up under the console and look at the fuse block. I pull out each fuse and they all seem okay. I go to the back and check the fuses and circuit breaker on the wires connected to starting battery and they all look good. I go back under the console and start snipping wire ties and cutting tape to see if there is an inline fuse on one of these wires. There are so many wires in those harnesses and there are jumpers and splits. I got the multimeter out and start testing circuits and the red wire to the switch is definitely not getting power to it. I try to follow the wire and it just seems to go everywhere. I do not find any inline fuses.

It is getting late so I now know I am not going fishing in the morning. I get up in the morning and go back under the console and again try to follow the wires. I built a jumper wire with an alligator clip to get a power feed to the positive connector so I can test if my new layout works. It does not. I unhook the power and do another swap and hook up the power for another test and I finally have it hooked up correctly. I unhook the power and now go more slowly to try and trace the red wire.

I get it to where it goes to the main bundle that goes to the motor. So I go back to the motor and pull off the cowling. I follow the path and find the red wire (it is actually Red w. Purple stripe at this point). I am looking for an in line fuse and do not see anything. I finally follow it to a little black box and it has a label "FUSE". I pull the wires from the box and sure enough there is the 20 amp blown fuse.

So what I learned is pull the switch before you order it so you can see what it looks like. Next unhook the power while you are messing with the wires. I also learned that there is and where the fuse is in the motor. I did not write down the final configuration. I do remember the R/W went to the Magneto Circuit, the Purple was the Ignition, I think the Y/B was Choke so the B/Y went to the Solenoid. And finally don't do something like that the day before you plan to fish.