What is this plug?
 

I was stupid and failed to mark a wire harness plug when doing a Non-Seq w/blockoff plate conversion. There is a plug on top of the engine behind the Alt. and the Thermostat housing, it has a roundish plug housing, its black and it is only a single wire/connection. I can't figure out what it went to. Please help. I'll try and get pictures of it with my phone later.

Water thermo-switch. Black/red single lead that almost always breaks off sometime during the life of the car.

The green plug is the ECU water thermo-sensor, which is different, and 2-lead anyways. The black plug connects to the water thermo-switch switch next to it.

Its not that, I have the thermo switch already hooked up (and broken of course), its something else. It looks like the female side of the plug. Its a black cover, and round, no color on the inside of the plug. I'll take a picture of it if I can, but any more answers will help greatly.

it could either be the water thermosensor, or the coolant level sensor the thermosensor is above the thermoswitch

Take your pick:

http://www.anodized.com/~clayne/fd3s/masochism.01.jpg

If it's the one with the white piece of plastic on it then that goes to the knock sensor.

here it is....I was thinking it might have had some kind of color in the inside, but it prolly broke off.

Knock sensor. You can see the part where the plastic tie-wrap insert goes.

nope not it. Knock sensor is still plugged in, that has a flat top side, this is completely round plug. Man this is confusing.....anyone, anyone..... bueller?

oh ya this may help, splits on the harness at the same spot with the green thermosensor plug on the back of the thermostat housing.

It goes below the green thermo sensor on the thermostat housing

Yeah, I think it is the the themoswitch, regardless it is behind what mazda calls the "water pump and pump body", see page E-16. It is behind the protrusion that the airpump mounts to, right around the other switch behind there, it's not too hard, it's the only round connecter in the engine I believe.

Jon

And we're back to square one - which is what we said in the first place, oneluv - the thermoswitch.

I don't get it, if you only have one harness plug remaining, what's the issue?

I was mistaking what you meant by the thermo switch...I will have to check it to see forsure, but I thought the there were only 3 things that hooked up to the house, 2 plugs in front, and the green one in back. I check again...I prolly just looked past it. thanks guys