I was told it was the factory fog light harness, but I'm not 100% sure. It had some bright colors, right? Yellow and blue maybe?

The thing i was looking at, attatched to the thin plastic flap that tucks up behind the bumper, and around the bottom of the radiator. It's black, about the size of an A-corn, and has four prongs which clip inside a hole about the size of a dime or nickel. Inside the prongs, it resembled the center electrode of a spark plug, just plastic. Am I looking at the right thing?

 

No, I think we are talking about the same thing, based on your description. Here is the one I'm talking about. Just to the lower right corner of the cooler.

 

Yeah, that's the thing I thought was the fog light harness...

My alleged temp sensor isn't really visible unless you pull the passenger directional, and look on the back side of the plastic "Chevy" flap or shrowd (visible in your picture), at the part where it wraps upwards. It's right near the larger circular hole, that has the clip in it. The sensor side faces inwards towards the grille area, while the wires are on the back-side facing the lights. I believe this is all just below/behind bumper level...

Maybe I'm wrong here, and there was another one of these on the other side. I'll take a look in a bit, and see if I can see anything. I really don't recall there being one...

I only took note of this one, because it came unplugged on me, and that plastic was unclipped.

 

If your talking about what I think you are, there are airbag looking pictures on it. I think they are the airbag frontal impact sensors.

 

I found all 3 sensors/connectors on mine...
The airbag shock sensors (under/inside the bumper) have orange tie wrap things on them. There are two unconnected weatherpak connectors for fog lights strapped to the bottom radiator frame rail inside the engine compartment. And, the temperature sensor is a little black plastic doodad with blue/green connector - located same place shown in Ben's pic, in front of the radiator.

 

I saw the airbag sensor... it was a little box bolted to something real solid. (frame rail?)

I assumed the harness in front of the radiator was just a capped off connector.

The other piece I was talking about SURE looks more sensor-like.

I'll get under there tonight and double check myself.

 

Stick a lighter to the sensor in my pic for a sec and check out the temp in the rear view. That'll crack the code for sure.

 

GM part numbers: 015047946 sensor @ $14.90, 015149708 retainer @ $4.86

plugs into the harness on the lower left side of the radiator support

 

on 03-04 models it is located on the driver side behind the grill, attached to the oil cooler support bracket, it is black,grey and green, and there are only two wires running from it, i believe. the cheapest i've seen those mirrors are about $285. I would assume you could move the sensor from the bracket and mount it in the air tube, and that would give you the IAT, but like it was said earlier, dont know if it would update fast enough to be useful. Sweet idea if you can get it to work though.

Wonder if a digital temp guage they use for amps would work???? Food for thought...

 

It was in the same place on my 02.