Thermostat Needle Stuck on HIGH...Help...

[J30SeriesVTec]

Ok well my g/f's mother has a 1997 toyota corolla CE with a 1.6l. Its very well taken care of. Has 112k and runs great. But the other day we started it and i looked down and after 5 minutes i noticed the temp needle was all the way up past H. I said holy skit, and told her to pull over, I got under the hood and motor was not that hot. I checked the coolant and it was full. So i thought maybe its the temp, switch/sender. So the car sat for a day then I just put the key in ignition and the needle was all the way up still with the car off and ice cold. so i replaced the coolant temp switch/sender and flushed the radiator, and still the same thing, and yes i did reset the ecu after replacing it. Any help is really appreciated my g/f's mother is freaking out thinking her car is done for. So your help is greatly appreciated.

[REN69]

I think the needle itself is fuxored.. try banging the dash to see if the needle will reset. If not, find her another cluster.

[karazy]

There may be a short in the wire, or you may have installed a defective part. If the needle drops when you unplug it, the new part is probably a dud. If it stays high, then I would check for a short, before you start pulling the dash.

[J30SeriesVTec]

the needle itself is not stuck because when u take the key out it goes all the way back down, then when u put it into ignition it goes str8 back up.

[J30SeriesVTec]

I read that the engine wiring harness on this model and year car are known for going bad or having problems, does anyone think this could be the culprit, and if it is, how do i go about checking it.

[J30SeriesVTec]

I would appreciate even the smallest suggestion...

[Hemi3TC]

Well as you said if the engine is cold and U turn the ignition on and the Temperature
gauge reads RED Hot, then yes yiu have a problem. If you disconnect the wire to the
temperature sensor it is still the same, RED Hot reading. Then you have a short somewhere
along that wire. So check that wiring harness all the way back to the temp gauge. Have someone watch the gauge while you
inspect the harness as you lift it the short may go away and
that is about where your problem is unless you yank hard it
may be a miles away.

Grounding the temperature sensor wire has the same effect as a short.
0 ohms = high temp. what ever resistance = low temperature.
got mulitmeter?

h3tc

[retiredat44]

I had a totally bizarre problem with our 1989 Corolla. I was adjusting some stuff under the hood, checking the a/c and all of a sudden the High temp gauge needle went to high. I was freaking out. The engine was not hot either, It was just normal warm/hot. But defiently not overheated. It was full of coolant. I went down and put in new Temp sensors. There are 2. One for temp and another for some other coolant temp esensor (I forgot for now) one is normal size and he other is tiny. It fixed the problems and all when back to normal. It was really shocking. We had the car for 11 years when it did this. To this day I have no clue when the temp sensor(s) failed. I did not want to chance anything bad with the temp system, and had to make sure it did not malfunction as my wife drives it and can't have it burn up over a smal part. I had replaced the radiator with a new one a couple months earlier. The old radiator had started to leak from old age. I had read somewhere that on MR2 engines sometimes they can have a pocket of air trapped. But that did not make sense for my Corolla, because at least 2 or 3 months had passed since I changed the radiator and had the coolant system open to air.

To this day I don't know why it screwed up. But replacing those sensors fixed thetemp gauge going to high problem.