Replacement Key Switch for 1974 Merc 165

[kckranz]

***Found a couple posts using search for Merc 165 wiring, but they mostly covered OEM switch wiring, or did not match my OEM wiring diagram***

Bought a new switch to replace rusted out one and am having trouble equating terminals. I have attached a picture of the new switch "instructions" and OEM wiring diagram. On the OEM diagram, I do have the optional accessory fuse panel wired for lights, horn, etc (this is note 3 on the diagram). Would this accessory fuse panel be switched? I need it to be.

Otherwise, I just need to wire for key switch on = power to accessory fuse panel, and key switch position 2 to turn the starter motor. I think I've stared at these diagrams so long I'm so confused. I don't really trust the letter designations, I'd rather see what the terminals "do". Can anyone help?

I can't post the pictures - says I am not authorized, but here is the link to them in Google Photo: https://goo.gl/photos/7c1o4nCQJ9Qo2QFQ6

 

[alldodge]

Howdy Kevin

You cannot upload pics until you make some more post. Looks like you bought the wrong ignition switch. Note the terminal "M" which is for Magneto. A magneto is only used on outboards with a 2 cycle motor



Your need one like these

http://www.iboats.com/Ignition-Star...24557428--session_id.986017095--view_id.39653

Note with these switches there is a 3 and 4 position switch. The 3 position is what is shown being wired. The 4 position has the accessary position

 

[kckranz]

I really appreciate it! I will order the four position switch. It looks like I will wire my 12V accessory fuse panel to the accessory post, but what about the other three? Given the OEM diagram, it doesn't make sense to have the white lead to connected to 12V battery terminal since it provides lights to the gauges, which should not come on until key switch is on RUN. Also, I get the position ACC, but isn't it redundant to the RUN position?

 

[alldodge]

The accessary position is used to connect things like a radio or 12V outlet only. Everything else gets connected to the run side. When key goes to run (ON) it connects everything on the Acc post and the run post. Most boats today do not use the Acc position, they use separate switches to turn each item ON individually.

The wiring you have is Pre BIW color codes.
Yellow - Start power to solenoid
Red/White - Battery power from Amp Meter
White - Ignition Power





If it was mine I would get the 3 position switch and run accessary power from another switch coming from a fused buss bar or from individual ones. Here is current pattern

 

[kckranz]

Thank you very much for this information. I understand everything everything in your post. Will print this off and place in my binder.