Heat sensors?

[flyboyo2]

Another puzzler, my '89 75 HP Mariner has what appears to be two heat sensors.  One lead comes from the port side of block next to the cylinder head and goes to the warning module.  The other is at the one o'clock position of the top spark plug and goes to the console where it has been cut, there is not gauge.  My guess is the former is water temp and latter cylinder head temp.  The  warning horn is kaput.  Is there a preference as to which is more important?  I'm attempting to post pixs.

Any ideas as to a replacement horn?

[Capt. Bob]

I'm not a Merc guy but the bottom pic looks like a water pressure connection to me.

[flyboyo2]

The fitting does look like a water pressure tap and the black lead has tubing inprinted on it but it's only about 1/8 inch in diameter and is connected to a larger multistrand wire in the console.  The tubing in the top picture is protective and an inner wire is connected to the warning module terminal block. 

[Capt. Bob]

Well you got me there. 
The tubing itself could have a small diameter but.....if it really is a wire........

It sure looks like a compression fitting to me.

Like I stated before, I'm no Merc guy.

[flyboyo2]

Again, you are correct, sir.  It is tubing made by Imperial Eastman for aircraft applications.  I must have lost tract of it going forward because it should connect directly to a pressure  gauge should it not? The thick wire I thought was the bitter end of the tube must be somethig else.

[Capt. Bob]

Yes, it would attach to the back of a pressure gauge.