alright i've been given the run around by all 3 auto parts stores and 2 dealerships... my old sensor cracked so i just got a new one and now my guage is staying all the way down. the water pump sensor is working fine (per my laptop), but heres the deal. The new guage i put in has 2 pins on it inside the oval plastic on the end. the pins are in a T-shape: one pin is going sideways on the side, one pin going the other way in the center. my harness that connects to the sensor only has one wire (connects to the pin on the side) I was told that i probably had a 1 pin sensor, but i cant remember and threw it out. the dealership told me that the 2 pin sensor can also be used in 1 pin applications but doenst explain anything. I got a wire through my harness and grounded the second pin (in the middle) and the guage just pegged all the way up and the "check gauges" light came on. I cant find a 1 pin sensor anywhere or a 2 pin harness that plugs into the new sensor. the only other thing was that i used a decent amount of teflon tape on the sensor when i put it in. could there be a bad connection to the block?

 

You need to get the same exact sensor that is your problem.

I got the run around when I broke mine as well. Took me three tries to get it correct.

 

The sensor that threads into the driver's side head is part #: 25037332 (courtesy shbox.com)

Give this to your parts counter guy and tell him to stop being a moron and do his job, they are not interchangeable. God I hate dealerships....

 

Oh, hey, that 2 pin sensor you have is probably a 1 pin sensor, (the correct one for the cylinder head). One of the pins, (I think the larger centermost pin), is just a guide and does nothing.

Yea, just take off that teflon tape and get a good ground to the engine. You already did all the checks on that wire and your gauge is good but the sensor isn't grounding to the block.

hth
Karl Ellwein

 

the dealership guys are idiots. the 2 wire sensor is the coolant temp sensor (used for the computer, mounted on the water pump). the "switch" you need, is the coolant temp SENDER. a 1 wire switch, sensor, whatever.mounted on head. a 2 wire sensor WILL NOT work.

 

just go to autozone or oreilys and use these magic words. "i need a coolant temperature SWITCH for the GAUGES". they will understand that. I been down this road a million times. about 10 bucks.

 

truth. It took quite a few trip to the parts store for me to figure this out.

 

Instead of editing my post above, I'll fix it here with another,

Oh, hey, that 2 pin sensor you have is probably a (1 wire sensor), (the correct one for the cylinder head). One of the pins, think the larger centermost pin, is just a guide and does nothing. The small pin is for the 1-wire.

The water pump temp sender has the 2 pins of the same size I belive and they are for the 2 wires. LOL.

So back to the taking off of the teflon tape.

Karl

 

thanx guys. yea that makes sense about the center pin just being there to guide it in. get this...after trying to ground it and having the guage peg and the check guages light come on...i ungrouded my wire and when i turned my car on, my guage was working. so i cant figure out exactly what caused it to not work, maybe i tripped something, who knows, but it is working now.

 

I changed over to a two wire sensor so that the computer and the gauge both read the temp at the pump and not in the head where the reading is inconsistent. I got the sensor numbers off the "Herd" site.

 

did you tie the wires together (did you tie the head sensor wiring to the pump wiring)? if you did that and eliminated using the head sensor, would that mess up the reading at the guage or what the pcm thinks the temp is?

 

John D, Help!!! Please don't start a trend here with the Fbody to follow that funny B-body impala SS HERD logic.
I don't know why you wouldn't want to see the cylinder head temperature. That's very important temperature. Water pump temp is nice but the heads make the heat and that's where you'll see an overheat condition 1st. So for early warning it's a good idea to look at the cylinder head. funny thing, the GM factory allowed us to do that. Thank God.

Karl

 

You pays your money, you takes your choice. If I was drag racing I sure would want to know the cyl head temp but for my use, block temp works for me. How many LT1 owners have you seen freak out about what the temp gauge does in stop and go traffic? I've probably seen that question as much as any I can think of.

 

thing is, when that cylinder temp gauge is moving, it's telling the driver the true temperature of the engine. If it moves too much I think it's prudent to freek out. A fix for that should be venting the system.
Karl

 

it would throw everything outta wack! dont try it. replace what needs to be fixed and forget about it. this is too simple a problem to try to alter the factory wiring.