What's the wire next to the thermostat?

Short story, haven't changed thermostat in about two years and it's been sticking really bad. Well last night went to pull a friend out of some snow and truck started overheating...BAD. Engine is as fine as it could be suffering 250 degrees but I was tapping away at the thermostat and because of the cold I broke off a wire plug that's right near the thermostat. It's on the passenger side and slightly forward. I use to think it was the temp sensor but it's not becasue that still works.

Simple answer would be wonderful!!!:)

It's a ground for something. Trying to think back to my 91.... I thought it was for the CTS.

It's a ground for something. Trying to think back to my 91.... I thought it was for the CTS.


No, the ground is on the driver side of the truck and it connects through the one bolt that holds the thermostat housing to the manifold. The one I'm talking about has a greenish bolt threaded into the manifold, and the wire is a two wire plug. It has a clip on it that unplugs but it's broken clean off. I might go out and take a picture tomorrow with my cell phone if that works, or I'll do it at night for a better picture with some light.

Pictures always help!

That description still sounds like the CTS.

The wire you broke is the temp sensor for the computer. On that year(1992) there was a temp sensor for the computer and one for the gauge. The gauge sensor is in the driver side cyl head. Probably you broke the top off of the computer sensor. Usually this happens when you change the thermostat because it is so close to the therm. housing.

A new one was 14.00 at oreilly's the other day for my '89. It'll make your truck run rich all the time until you replace it. That's the secret to the curing the high idleing 88-93ish trucks.

Thanks a lot guys, I thought it was the temp sensor but when my gauge still read I wasn't sure. I'm going to O'Reily's for the thermostat so I'll check out the sensor too, thanks for the help guys!

All fixed now. Total for thermostat, gasket, and sensor was 12.81. Got another question though, the temp sensor doesn't go down all the way, I noticed the old one only took 6-8 turns before it came out, the new one I turned probalby 15 or more times though yet it's still not all the way down. I assume this is ok as there is 1/4" of that paste on there and there is only 1/16 of it showing. Picture:
http://img264.imageshack.us/img264/4344/untitled7863jq.th.png (http://img264.imageshack.us/my.php?image=untitled7863jq.png)

Also, I let my truck warm up to about 150-160 then drove it and after about a mile of light driving it was up to about 200, so I stepped out to top it off with coolant as it looked low but when I popped off the rad. cap coolant splurged up out, luckily it wasn't more than 90 degrees. After that I put cap back on and poured some coolant in the puke tank and got back in truck. Temp sensor said it was running about 220, started to drive and it went back down immediately. I'm assuming it was just measuring air temperature as the thermostat hadn't completely opened to allow coolant to flow through. Got back home though and the puke tank was damn near empty.

Before we put the new thermostat in we compared old vs. new by putting in boiling water on the stove, that old one opened maybe 1/3 of what the new one opened, no wonder it over heated.:rolleyes:

The Sensor that you broke and replaced is the sensor for the ECM not the sensor for the gauge.

It is normal to see some threads of the sensor.

The sensor for the gauge is in the drivers side head so yes it could have read high until the tstat opened up and allowed coolant to fill the system.

Check your overflow tank often for a few days and top it off if it is low.

//2000CAYukon

For next time here is a tip to avoid the burping and emptying the coolant reservoir--Drill a 1/15 to 1/8 hole in the thermostat. This allows for the engine to fill completely, purging the air .