Coolant Temp Gauge Problem?

Question

My '86 Celica GT-S temp gauge is "flickery" Sometimes it will be all the way hot, all the way cold, and sometimes it will be in the middle and be right... I cleaned all the terminals, replaced the coolant sensor and sender (not knowing which did what) and it still is doing the same thing. Flushed the radiator and engine. All the other gauges work. Is there a 3rd sensor that im not aware of? Im pretty good with cars but this is stumping me... BTW. the car has 149,998 miles on it =]

Answer 1

I have had this many times on this model car and you almost had it....

the plug in terminal that goes on the sensor spreads open and is loose. one minute it makes good connection- other times it doesnt and makes the resistance reading go nuts, causing the gauge to flicker wildly at times with engine vibration.  You need to get a small pick or screwdriver and pull the metal part of the connector against the tiny cleats on either side of the harness connector so it goes on real snug. Some WD-40 may help the electrical connection. Do that and the problem will go away. Good Luck,  T&T

Answer 2

I had a similar problem with an oil pressure gauge once. I eventually discovered that the wire connected to the sender would occasionally bump against the shifter linkage and short out. I wrapped it with electrical tape and secured it away from any moving parts. I can't promise this will solve your problem, but it's an easy thing to check for.  

Answer 3

u have a bad water temperature sensor.. if its was a faulty connection it should only jump to its average temp. if it jumps into the redzone than drops way back down get a new temp sensor.

Answer 4

its probably your thermostat hope this helped you