I have been trying to figure out what this connector goes to for months. I took it to 2 specialty hybrid shops and they told me that sometimes there are just extra wiring harnesses. That makes zero sense to me. It's on the back of the radiator, close to the air intake box and to the right of the windshield wiper fluid if facing the engine. Also when I hook up my ODB2 port reader no air conditioning information comes back. I have a hunch it has something to do with that. I have consulted the Chilton manual to no avail. What is this mysterious harness? Thank you so much!
Whatever it is, mine has the same connector. Obviously, it’s for something not included in my equipment options. Toyota only knows. Someone with a fully optioned model 5 may chime in and give you some insight. Who knows?
On mine I think that goes to the knock sensor. It's easier to see if you get some of the air intake stuff out of the way. The sensor itself is kind of hidden on the engine block behind the intake manifold (which is a bit involved to remove, I wouldn't recommend that just for inspecting; mirror on a stick or phone camera should be good enough). There should be a short little stubby cable that runs from the knock sensor on the engine block with its other end attached to a little metal bracket sticking out at you (attached to the engine at one of the anchor points for the dipstick tube). That little bracket should be holding the free end of that little stubby cable right out at you where you can reach it at plug that connector onto it. Or, have you had any work done where somebody might have removed the stubby cable and forgotten to put it back? I think it's about $16 at the dealer if you need it. The knock sensor protects the engine against 'detonation', an abnormal form of combustion that can do mechanical damage. So I wouldn't want to leave it unhooked any longer than necessary. I would be a little surprised if you don't have an engine trouble code saying "hey where's my knock sensor?".
Okay so the knock sensor isom the right hand side by the air intake manifold according to chilton. Then there is this very odd space where I've seen something coming out in videos and after looking FOREVER at engine schematics and wiring I found one that winds its way through to the firewalls and is secured here by one of those demon clips in black that. And it had something to do with AC feedback of fans. Of course I can't find it now. I sound maniacal but it's driving me crazy. Why would there be a wiring connector attached to nothing?
You might have your directions confused. I'm fairly certain that isn't a knock sensor wire; it's nowhere near the engine. The front of the car is toward the top of the picture; that connector sticks out of a wiring harness that runs along the radiator support. Mine (2013 Two) has it as well. I suspect it's for adaptive cruise control or lane departure warning hardware that doesn't exist on plebeian trims. On lower trims there are unused connectors all over the place, such as those for the JBL tweeters behind the rear door panels. Cheaper just to manufacture one harness, I guess.
Yeah, that's possible ... I've got my bearings now, thanks. Anyway, since I brought up the knock sensor anyway (and I'm not sure I can picture where Chilton is saying it is!), here's a picture. I found it on a thread about replacing the PCV valve (seen in its shiny valvulent glory right in the center of the frame), but right there to its left, easy to see with the manifold off, is the knock sensor, with its stubby little cable brought out to a connector attached on that dipstick-tube standoff, where you at least have a fighting chance of reaching it to plug in its mating harness connector (shown disconnected below it in this photo). If that doesn't solve the mystery of the Mystery Wiring Connector, and if Gearedgirl is interested enough in solving it, this post steps through the sure-fire way to do it. Naturally, under Location & Routing, you would start under Engine Compartment rather than under Body.
Without resorting to anything like a wiring diagram, I have a hunch this is for the low-washer-fluid sensor, which is infuriatingly only a thing in Canada. (I would love such a sensor, as I always seem to detect low fluid by running out just a few miles into a cross-country drive behind a truck on a 1-lane road in sleeting weather.)
