Temperature Gauge [Archive] - GrandAmGT.com Forum

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Metallman56
11-27-2006, 06:32 AM
i did a search, but didnt find what i needed. this has happend before to me. i'm just driving along and all is fine when i look down and my Temp guage has dropped to 100*. it wont move from that spot. it stays like that for a couple of days and then comes back to normal. this problem isnt a real big deal, but with it being winter, it would be nice to know when i can turn the heat on in the morning. if anyone else has had this problem let me know.

thanks guys :cheers:

lastryghts
11-27-2006, 06:51 AM
T-stat possibly sticking open? Otherwise I would guess your sending unit is going bad.

Metallman56
11-27-2006, 06:53 AM
cross off the T-stat, cause i get hot air. its like 1 second i look down and i'm at 190*, and the next i look down at its 100*. the odd thing is, is that it stays at 100*, no lower or higher. so its getting some sort of signal.

Sprucegagt
11-27-2006, 07:12 AM
Broken wire or bad temp sensor.

iceman
11-27-2006, 01:30 PM
I have the same thing on occasion, when I scanned the code it was for low sensor voltage.. basically bad sensor or wiring like Andy said. You'll probably notice your high speed fans kicking on as well

Metallman56
11-27-2006, 01:40 PM
i havent noticed the fans kicking on or off or anything else wierd. huh. so this isnt really that big of a deal is it?

Sprucegagt
11-27-2006, 02:13 PM
There is only one coolant temp sensor on the engine. So yeah it is a problem if it's not working right. One problem is bad gas mileage due to the PCM thinking the engine is cold when it's really not.

Metallman56
11-27-2006, 02:15 PM
where is the temp sensor? isnt it on or by the throttle body?

Sprucegagt
11-27-2006, 03:01 PM
Close, it's right beside the t-stat housing on the LIM side.

Metallman56
11-28-2006, 06:12 AM
hmmm. . . i would check it, but my gauge works again now. i didnt do anything, i was just driving looked down and its on. in 6 months when it goes out again, i'll tinker with it.

thanks guys :cheers:

slowbird
11-28-2006, 08:35 AM
I thought there were 2 Sensors.

The one for the Computer and the one for the sensor.

slowbird
11-28-2006, 08:35 AM
Atleast my 3.1L was like that.

Sprucegagt
11-28-2006, 09:36 AM
I believe the 3.1 does have 2 sensors, but it changed to 1 on the 3400.

Metallman56
12-02-2006, 06:49 AM
well its doing it again. great. just when i am really pressed for cash.

tjc13
12-02-2006, 07:27 AM
They're not very expensive, it's a part that you can get at Autozone. Just make sure that when you change it that your engine is cool, because if it's not you'll have hot coolant everywhere.

bulet225
01-08-2007, 04:46 PM
My daughter's 01 GT is doing the exact same thing. I changed the temp sensor and it is still doing it. Wish I had a clue of what it is?
Thanks for any help.
Vince

Sprucegagt
01-08-2007, 08:14 PM
Since I made my post, I have had this happen to me as well. Now it happened to me a day after I pressure washed the engine. So moisture could be part of the problem. I wasn't able to tract this down for sure because by the time I got home and hooked up my scanner, the gauge was acting fine and the PCM was getting the proper temp signal. If it happens again, I'll try to dig further into this.

bulet225
01-10-2007, 08:35 PM
Thanks Spruce,
The temp gauge has now turned on the check engine light saying that the coolant temp is too low. I guess the pcm works off the temp gauge reading instead of it own sensor. I will have to look into this further as time permits. I will let ya know what I find.

gectek
01-10-2007, 10:35 PM
usually if it is coolant temp too low, then it is a code just for the thermostat only, i think its code p0128? that code was made for the thermostat efficiency and thats about it, unless you have a bad temp sensor, those would be the only things

tigersgt
01-27-2007, 06:04 PM
Ok, I have had the EXACT same problem as you guys. Temp gauge not registering, high speed fans running ALL the time, and then......after a few days...service engine soon light. Had autozone check the code and it said "coolant temp sensor below low limit" or something like that. Bought the $10 sensor from autozone and changed it out. STILL no temp registering on gauge. What the hell could it be? It isn't the thermostat as I get hot air out of the hvac system after car's been running for only a few minutes. Please help!

gectek
01-27-2007, 11:17 PM
maybe a lost ground or open wire from sender to gauge, does it self check when i turn the key on

ryansGrandam
01-29-2007, 07:59 AM
I have the same problem the bad thing is it only does it when the temp is about 20 or lower. When it does it i can tell the fans kick on cause lights dim 4 a sec. so as soon as u guys find out it would be nice cause im tired of it to.

bulet225
02-16-2007, 05:17 PM
Hey guy's,
Has anyone found the problem yet? I went and bought a new temp sensor from the Pontiac dealer ( Hoping the one from autozone was causing the temp gauge not to work) But it is still doing the same thing. The high speed cooling fans kick on as soon as the car is started.

gectek
02-16-2007, 07:50 PM
maybe a lost ground or open wire from sender to gauge, does it self check when i turn the key on

^^^check this...does it do that

bulet225
02-17-2007, 06:16 AM
Yes,
The temp gauge does do a full sweep win the ignition is turned on. I am going to try and trace the sending unit wire back as far as i can and check with an ohm meter to see if any are broke.
It's my last resort before I take it to a real mechanic. LOL

Sprucegagt
03-10-2007, 06:56 PM
Hey guy's,
Has anyone found the problem yet? I went and bought a new temp sensor from the Pontiac dealer ( Hoping the one from autozone was causing the temp gauge not to work) But it is still doing the same thing. The high speed cooling fans kick on as soon as the car is started.

I ran into this same problem but found the fix for it. The coolant sensor was bad in my car but after changing the sensor my gauge still would not work. Turns out I had some DTC's set that were not turning on the SES light. The second I cleared these codes my temp gauge operated perfectly and the high speed fans turned off. If anyone runs into the problem of the temperature gauge going dead I would get the car read for trouble codes even if the SES light is not on.

iceman
03-12-2007, 10:19 AM
Yep, I cleared the codes I had as well (1 O2 sensor one, 1 coolant temp one, one for needing a case learn, I forgot to write them all down) and the second I did that, the gauge started to work. However about 20 minutes later it broke again, so I'll have to change the sensor and then try again.

Napa has em for about 30 bucks last time I checked

JC_76
04-10-2007, 04:31 AM
Ok my car is doing the same thing.The fans turn on as soon as I turn the car on and the temp.needle is all the way down to 100. What is the name of the sensor that fixes this problem? What does the sensor look like and where is it located? Anyone have any pics of the location of this sensor?

gectek
04-10-2007, 10:44 AM
coolant temp sensor and it is pointing to the front of the car on the lower intake manifold right on the thermostat housing (the intake side)

JC_76
04-10-2007, 12:35 PM
Is that the sensor that is located right under the throttle body?

gectek
04-10-2007, 01:18 PM
pretty much yah

Metallman56
04-10-2007, 01:37 PM
has anyone experianced this problem after both replacing the sensor and clearing the trouble code? just wondering, cause guess what? yep, its out again. and it only happens when its cold out. i wouldnt mind it in the summer, but when its freakin freezing in the mornin, i dont know when i can turn the heat on, and get heat.

JC_76
04-10-2007, 02:34 PM
I replaced the sensor yesterday and cleared the SES light code by disconnecting the battery. The gauge was working fine and the fans turned off but on my way home from work it acted up again. What the hell could be the problem? Or maybe I changed out the wrong sensor. It was a $12 sensor from Autozone and goes right below the throttle body. Anyone know the part # for the right sensor? I just want to make sure that I changed the right one. I will post pictures soon showing the sensor that I replaced and where it is positioned.

Sprucegagt
04-10-2007, 02:48 PM
I don't think disconnecting the battery erases the codes stored in the PCM history. That's were the code is that's turning off the temp gauge. You won't have a SES light if it is only in the PCM history. You will need a handheld scanner to erase the code. Autozone will do this for free if one is around you.

JC_76
04-10-2007, 02:57 PM
Thanks for that advice Spruce I will try that next since my Autozone has the machine. Here is a picture of the sensor and location. Let me know if that is the right sensor that I changed out. It was a Wells sensor part #SU109.

iceman
04-10-2007, 03:04 PM
Yep, that is the correct one.

JC_76
04-10-2007, 04:07 PM
Ok I just got back from Autozone and they would not clear the code. They told me just to disconnect the battery but I dont think thats gonna work since I already did that yesterday. I guess my only thing to do is take it to a shop and pay to get the codes cleared and see if that works.

Metallman56
04-11-2007, 06:42 AM
they wont clear that code? thats :amraam: you might want to take it to anther autozone and just play dumb. say you've got a check engine light on, and when they tell you the problem tell them to clear the code. then leave. lol i've done that before.

Sprucegagt
04-11-2007, 09:01 AM
Ok I just got back from Autozone and they would not clear the code. They told me just to disconnect the battery but I dont think thats gonna work since I already did that yesterday. I guess my only thing to do is take it to a shop and pay to get the codes cleared and see if that works.

Tell the parts monkey at Autozone that you need your car read for codes. Then once he reads it, tell him to delete the code. Don't ask them at the counter to delete it.

JC_76
04-11-2007, 01:18 PM
Ok I got a friend of mine from work who is a mechanic to clear the code for me free of charge. The needle worked and the fans turned off but that only worked for about 20 minutes. On the way home the temp. would not read any higher than 150 and I was on the highway doing about 65. Then the needle just dropped and the fans kicked in again. I was doing a little more research and thinking it might be the thermostat. What do you guys think?

Metallman56
04-11-2007, 01:49 PM
my themostat is less then 2 years old. i hope its not.

Sprucegagt
04-11-2007, 02:32 PM
Ok I got a friend of mine from work who is a mechanic to clear the code for me free of charge. The needle worked and the fans turned off but that only worked for about 20 minutes. On the way home the temp. would not read any higher than 150 and I was on the highway doing about 65. Then the needle just dropped and the fans kicked in again. I was doing a little more research and thinking it might be the thermostat. What do you guys think?

That may be it. Has the thermostat ever been changed? Have you done a coolant flush lately?

my themostat is less then 2 years old. i hope its not.

Tstat can go at any time. Even brand new pieces can be duds.

JC_76
04-11-2007, 03:03 PM
My thermostat was changed a little over 2 years ago at the same time that I changed the LIM gasket.

Sprucegagt
04-11-2007, 03:08 PM
You may have a thermostat that's opening to soon. But before you do that. Check the wiring to the coolant sensor. Especially the connector pins. There should be no moisture or corrosion. Also make sure that you get 5 volts DC across the connector leads with the switch off and the connector unplugged.

izayn
11-15-2007, 06:24 AM
Does anything need to be removed to change the coolant temerature sensor?

iceman
11-15-2007, 06:32 AM
I got mine out w/out removing anything...

But will say this, problem persists.. definitely a wiring problem, just haven't really spent any time to look at it because I don't care much

BrianV
11-27-2007, 09:50 PM
I have this problem too and have a Palm Pilot based OBD2 scan tool (Dynoscan) that can show sensor outputs etc...

The gauge in the dash shows only 100 but the scan tool shows only one temp sensor and it reflects the right temps even when the dash gauge is reading 100.

If I clear all P0128's out -- the gauge in the dash works immediately. Unfortunately, I don't have any solution except to clear the codes.

Anybody got any ideas why this would happen?

Sprucegagt
11-27-2007, 10:04 PM
Did you bother to read the thread?

iceman
11-27-2007, 10:38 PM
Hey Andy, you know where the harness for the ECT comes from?? mine heads up towards the under throttle body area.. it's pretty tight I'm wondering if I pinched it by mistake when replacing the plenum last.

BrianV
11-27-2007, 10:46 PM
I admit I didn't read it all because I didn't realize there were 3 pages in the thread...I only read one page. Sorry.

Unfortunately, I don't see any solutions here though.

gectek
12-18-2007, 06:56 PM
the harness goes to the injector/cmp sensor harness under the UIM...it usually gets damaged easily because it is in such a dumb location with a short harness