What's this wire for?

[Swedefj40]

I'm in the middle of troubleshooting why my water temp gauge is not working and found these two wires (purple with plastic connector and a black one with a ring connector) not connected to anything but laying down on the intake manifold between the distributor and carb.

They go directly into the harness right there below them. Any idea what they're for? I'm assuming the black one with the ring terminal is a ground but the Purple one I cannot figure out what it's supposed to be plugged into. I recently replaced the starter slave solenoid which is right next to them. I'm not sure if I disconnected them from somewhere or they're just not used for anything.

While we're at it, my water temp gauge quit working the last time I was out. I pulled the connector off of the sender and grounded it to the block but the gauge didn't budge. I have 6.5 volts at the connector (Tan wire) and also at the post at the back of the gauge (Tan wire).

Gauge lights all work and when I switch the ignition key to "on" all other gauges move but the Water Temp gauge doesn't even flicker one bit.

Where do I go from here?

 

[Mechmagcn]

If you have power to the wire at the sending unit and the gauge doesn't move when you ground that wire, it's time for a new gauge.

 

[Swedefj40]

Did some more digging and it looks like the purple and black wires are not used in my application. Possibly used for an electric choke which I don't believe I use.

Now about the other issue of the water temp gauge, I removed the tan wire from the gauge and grounded the "S" post and had an immediate deflection on the gauge. I believe there is a continuity issue with the tan wire, possibly a poor contact in the main harness plug where it joins the engine harness as there was some change in resistance when I tried to move it around but I'm not sure, it was in the Meg-ohm range. I ran another wire directly from the "S" post on the gauge to the sender post and noticed a slight movement on the gauge. I then grounded the wire to the base of the sender and immediately got full deflection.

How do you get the main harness plug apart??? Is it a twist off or direct pull?

 

[wellcraft-classic210]

1 suggestion -- You may want to make sure your sender is grounded at the case ( threaded outer portion ) -- thread sealers can prevent that in some cases

Your boat is newer than mine so I am not sure about the connector disassembly

 

[Swedefj40]

Yeah the sensor's case has a good bond with the block. As I mentioned, that is where I grounded the test wire too to get the gauge's needle to deflect.

 

[Swedefj40]

I can't for the life of me separate the motor wiring harness from the boats harness at the big connector!!! Looks like it should just pull off but I can't get it to budge!!! Am I doing it right by just pulling it off or is there a set screw or clip of some sort that I'm missing???

 

[Swedefj40]

This is my nemesis at the moment...

 

[Bondo]

Ayuh,..... It should unplug with a wiggle, 'n pull,.....

 

[Swedefj40]

Yeah that's what I'm thinking too but it won't budge. I literally climbed on top of the motor and grabbed it with both hands and wiggled and twisted and even tried to pry it off with a screw driver to the point that I'm worried about breaking it off the mount!!! It just won't move.

 

[Swedefj40]

Well it moved...

 

[Fun Times]

Sorry to see your electrical troubles corroded over like that!

MerCruiser Style Wiring Pigtail - Mercury Plug, Instrument Side 12" part number 620-08813 is an option for a new connector,
https://www.hardin-marine.com/p-132...-pigtail-mercury-plug-instrument-side-12.aspx

Or, https://www.cpperformance.com/c-146-wiring-harnesses.aspx

 

[Swedefj40]

Lol I was just looking at those! Anyone know where to get something like them in Canada? It takes too long to get stuff shipped up from the States.

 

[Fun Times]

Lol I was just looking at those! Anyone know where to get something like them in Canada? It takes too long to get stuff shipped up from the States.

For Merc OEM search online or your EBay, etc., Item Number: 84-812475A3..,https://www.mercruiserparts.com/812475a3-harness-assy

https://www.ebay.com/sch/i.html?_fro...475A3&_sacat=0

Maybe by chance Yegboats would be able to see this and help via PM as she's in the Western Canada area.

 

[Swedefj40]

I ended ordering from cpperformance. Thanks for the help.

 

[metsfan3197843]

That is some nasty corrosion. Anyone have a recommendation for prevention. Dielectric grease perhaps?

 

[Swedefj40]

Well here's an update... soon after I ordered the new plug I went to pull the old pins out of the female end and ended up pulling out the contact portion of the female plug with it. This happened to the other two pins as well so needless to say I need the motor side plug now too. Well screw that! I instead ended up using 2 multi-pin "woodhead" connectors and butt spliced them in. I used heat shrink type butt splices, Penetrox on the joints and again covered them with more heat shrink. I added Die-electric grease to the connector and then fired it up. I don't know why but it started up instantly, much quicker than normal. At any rate I'm happy with how it turned out and I saved a ton of money too.

 

[wellcraft-classic210]

Yes -- Dielectric grease would be a great idea !

Just curious -- are you running in salt water ?

 

[Swedefj40]

Yup