Cooling system: sensor without a wire

[Montego Murph]

Hi all,

I've got a mystery of sorts with my 2003 V8. My shop manual for some reason doesn't identify either of these things. (More than likely, I'm not searching correctly and the folder structure setup is a little unnerving.)

My last two fill ups were 13 MPG whereas I usually get 17 or 18 all highway, 50-55 mph. ("Blah blah blah, if I'm concerned about MPG I should be driving a Prius.") so that's what led me to investigate. I realize these are gas hogs by design, but I still want it to run as efficiently as possible with all the driving I do.

I decided to investigate and noticed that I had a split vacuum line going from the air intake hose to this component in the lower right corner of the photo, (which I repaired) and then this plug with no wire in the upper left which seems to be a cooling manifold. Is this just a test port or something? I'm guessing it's some sort of temp sensor which could feasibly be related to fuel mixture or something. No stray wires leading to it, but it seems very un-Toyotalike to just leave a connector like this where it can collect water and debris.

Off to search for "vacuum line diagram" and "coolant sensors"

 

[AuSeeker]

This is the V8 correct?, if so it appears that I have the same connector with no wire attached to it, but it's hard to see without taking some stuff off, but it looks to be the same as your's, not sure what it's for either, your's also doesn't look to have had a wire/connector attached to it in recent history if ever.

 

[Montego Murph]

Correct. This is a 2003 V8. I agree, it doesn't have any "makers marks" or anything to indicate that something was plugged in recently. I bought this from the original owner (my father) about a year ago and I figure in 15 years maybe some mechanic forgot to plug something in....

Maybe I should put a rubber cap on it to keep water from getting in there and shorting something out....

 

[AuSeeker]

With no wires going to it there is no way for anything to short out, it came that way from the factory so it should be good to leave it as is, it's possible it's for connecting a tester to get the coolant temperature when doing service work.

 

[Montego Murph]

With no wires going to it there is no way for anything to short out, it came that way from the factory so it should be good to leave it as is, it's possible it's for connecting a tester to get the coolant temperature when doing service work.

Now I realize I've been in the sun too long... you're right. Thanks for setting me straight!

Any idea what that vacuum nipple is for in the lower right? I'm searching for vac line diagrams now but no luck yet. I'm curious what vacuum leak I just repaired.

 

[AuSeeker]

Not sure on the vaccum line, it's raining here so I only ran out for just a second or two to look at the electrical connector and then the rain was coming down harder so I slammed the hood and ran back inside before I started to melt or float whichever came first!!