New at this need help

[frog man 63]

I have a Mercury thunderbolt 50 HP 500 series 1973 I need the wiring systematics for the key ignition also need to know if anyone knows where I can get a five stud three position key switch hope to hear back soon thank you

 

[Chris1956]

Go on the maxrules website to find a common wiring diagram for your motor. The 4 cylinder 50HP Merc was a real popular motor, so it was made for a long time. Try to find a wiring schematic close the year of your motor, as the wiring colors probably changed over the years your motor was made.

The keyswitch you need is a common item. A Merc dealer or an aftermarket place should have it. The posts are labeled, B, M, M, I, S. They probably correspond to the following wiring colors: Red, Black, Salmon or Orange, white, yellow. The choke wire is the white wire going thru the choke switch to the grey wire. The yellow solenoid wire would go thru the neutral switch, and then to the starter solenoid.

 

[frog man 63]

It's the key switch is the hard thing to find because it only has 5 post and 3 pos I will keep looking do you by chance know of any place that might have one the 3 code on it is 128 thank you for the info that you give me it will help

 

[brodmann]

I can't find it now, but I watched a video a few days ago trying to help someone out with replacing an ignition switch. The guy in the video said that a common after market ignition with 6 terminals would work fine, you just don't use the center one. He had an ignition switch with 5 terminals around the edges and one in the center. Lots of aftermarket igition switches on the market today are pre-wired and sealed a silicone gell. They come with wiring instructions specific to different manufacturers.

 

[Chris1956]

I will assume you have one of the old MerControls that came with the motor. Those had a separate choke button, and a 5 post ign keyswitch. Newer keyswitches have a 6 post ign switch, with the new post being the choke.

If you want to reuse the original control, you need to make sure you get an ign switch that fits into the MerControl housing, as the space inside the control is limited.

I would expect the ign switch to be available, as there were thousands of MerControls made for many years. See if you can look up a part number on a Mercury OEM parts site for an exact replacement for your switch and get the part number. Failing that you might visit your local Merc Dealer, as he will know the part number, and may stock it.

 

[frog man 63]

The number that is on the switch is 128 I am assuming that the three numbers are 3 number code that the dealership was talking about I will get a hold of them on Monday

 

[Chris1956]

Sometimes the number of the ign key that fits the lock is printed on the ign switch. 128 does not seem to have enough characters to be a part number.

 

[frog man 63]

Sometimes the number of the ign key that fits the lock is printed on the ign switch. 128 does not seem to have enough characters to be a part number.

Sorry for the long delay I have a lot on my plate but I have to get this boat running I have a 6 wire switch brand new is there anyway I can wire this switch up to work I have no wiring systematics for the switch it didn't come with one it has one red ,one black,one purple,one black with white stripe,one yellow with red stripe,and last one is a yellow with a blue or gray stripe and to tell you the truth I am Lost. I don't know why there 2 black wires I have an idea but I don't want to confuse myself anymore if you or anyone could please help I would be thankful hope to hear from you all soon

 

[Chris1956]

It sounds like you have the new wiring colors.
Red is battery power and goes to the "B" terminal.
Black is ground and goes to one of the "M" terminals.
Purple is ign power and goes to the "I" terminal.
Black/yellow is usually the color of the ign killer wire and goes to the other "M" terminal.
Yellow/red is the starter solenoid and goes to the "S" terminal.
Yellow/black is the choke solenoid and goes to the "C" terminal, or choke button, whichever you are using.

Grey is for tachometer signal.

 

[frog man 63]

Is there any new type of control box and wiring harness that would work on my old motor maybe a little modification but not to much I keep trying to find a control box like the one I have I can't find one to save my life I don't know what to do. There has to be a way for a new control box to work on my old merc thunderbolt 50 outboard I just hope someone tells me how

 

[racerone]

Your location?

 

[frog man 63]

I am in Gauley Bridge WV

 

[Chris1956]

The newer Merc compatible controls will work with your motor, with some modifications.

The control cables for shift and throttle should work w/o any mods. You should be able to reuse your existing control cables with the new control.

New wiring often comes with new controls and would usually need to be adapted.

Wern't you originally just looking for a new ign keyswitch? What happened to that plan? I have soldered in a new KeySwitch for my MerConrols on a number of occasions. Could you not find a replacement Merc ign keyswitch?

Heck, you could buy a universal outboard ign keyswitch, mount it on the dashboard, solder some ring terminals to the old ign wires and wire it up.

 

[frog man 63]

If I did it that way what would I do about the choke and the neutral safety switch I don't know why this has me so confused

 

[frog man 63]

Yes I could not find a key switch for it I looked all over

 

[Scott Danforth]

Yes I could not find a key switch for it I looked all over

Look it up by part number

 

[Chris1956]

I am pretty sure this is the one you need for a standard MerControl. If you visit a dealer, he will likely have one, or can get one.

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The solenoid wire, terminal "S", needs to be wired thru the neutral safety switch. The solenoid wire yellow/red, is wired to the other side of the neutral safety switch.

Ign power, terminal "I" needs to power the choke button. The other side of the choke button gets the yellow/black wire.

I used an 80W soldering iron, fine sandpaper and flux to help clean the wires so the old wiring harness would connect to the new switch.

Those MerControls have a steel roller that holds neutral. Careful not to drop it.

 

[frog man 63]

I already did drop it and had no idea where it went I still have it the switch info that you sent looks just like the one that I took out thank you so much.today I got another control box with everything on it but it's has 8 pins my nextdoor neighbor had it and he don't remember what it came off of he also has Merc 85 HP with everything on it and wants to sell it to me I am thinking about getting it just because he says it runs I will send you pictures of it let know what you think if that is ok with you i will order the switch tomorrow thank you again i will keep you posted