Temperature gauge fluctuates while driving - Hyundai Motor 1996 Elantra

Fiats have a reputation for electrical/electronic problems as they age and even when they are not very old they can manage strange things that even sometimes defeat the dealers, though the same can be said of many modern vehicles. I used to look after a Ducato motorhome and fortunately didn't need to get involved with much electrical work - the only faults were caused by the coachbuilders rushing around and being careless and not by Fiat.

I am not sure if the temp gauge is driven by the engine management or is a traditional circuit but either way the temperature gauge is in effect a voltmeter of sorts. Assuming the gauge is ok, the reading will only fluctuate if the voltage in the circuit fluctuates and that could mean the supply voltage is fluctuating or the resistance of the ground path is fluctuating.

With the traditional circuit the gauge is supplied by an electronically stabilised voltage and the ground path resistance is varied by the engine coolant temperature sensor and fluctuations could be anything from a faulty instrument voltage regulator, through faulty wiring or connections to the temperature actually fluctuating.

If the gauge is driven by the engine management the same approximately applies but checking the circuit becomes much more complex due to the need for circuit diagrams and specialised test equipment, though these would not be needed just to check the security of the gauge in the printed circuit of the instrument panel.

An accurate temperature gauge will always fluctuate because the temperature in the engine fluctuates.

Usually the only time this is really noticeable is when the engine has been working hard and suddenly has to wait at a junction or similar and the gauge can rise considerably.

You didn't mention by how much the gauge fluctuates?
As long as it remains approximately in the normal zone it is acceptable but if it climbs into the hot zone or falls into the cold zone it is not acceptable and the cause should be investigated as soon as possible.

check grill and radiator fins are not plugged and fan is not damaged and is working.
sounds like a thermostat or water pump issue.

First things first....
INSPECT COOLANT LEVEL
Low ????
PRESSURE TEST SYSTEM
PRESSURE TEST RADIATOR/EXPANSION TANK CAP
INSPECT DRIVE BELT(s)
INSPECT COOLANT HOSES
INSPECT HEATER HOSES
INSPECT BYPASS/MISC. COOLANT HOSES/PIPES
TEST THERMOSTAT OPERATION
INSPECT RADIATOR TEMPERATURE
INSPECT RADIATOR COOLING FAN(s)/CLUTCH OPERATION
INSPECT CONDENSER/AUXILARY COOLING FAN(s) OPERATION(s)
INSPECT RADIATOR & CONDENSER FOR DEBRI
OBSERVE COOLANT TEMPERATURE GAUGE OPERATION

If you need further help, reach me via phone at https://www.6ya.com/expert/ralph_2f0886b7d6af32ce

Check out related help links with solutions to troubleshoot the problem:---
Click the link below:---
2004 Toyota Tundra: Oil Gauge and Temp Gauge Not Working?

http://howtobyme.blogspot.in/2012/05/2004-toyota-tundra-oil-gauge-and-temp.html

---------
Toyota 4Runner: Temperature Gauge Sensor http://technoanswers.blogspot.in/2012/04/toyota-4runner-temperature-gauge-sensor.html

-----------
Temperature gauge sits over half way mark? http://schematicsdiagram.blogspot.in/2012/04/temperature-gauge-sits-over-half-way.html
----------
Heater blows intermittently and temp gauge goes erratic?

http://technoanswers.blogspot.com/2012/01/heater-blows-intermittently-and-temp.html
------------- No heat on Oldsmobile Silhouette? http://technoanswers.blogspot.in/2012/02/no-heat-on-oldsmobile-silhouette.html
-------------
Temperature gauge does not move and no heat when heater is ON? http://technoanswers.blogspot.com/2012/01/temperature-gauge-does-not-move-and-no.html
----------
Temperature gauge keeps fluctuating up and down close to red? http://technoanswers.blogspot.com/2012/01/temperature-gauge-keeps-fluctuating-up.html
----------- Temperature gauge on the dash quit working on Pontiac Grand Prix? http://technoanswers.blogspot.com/2012/01/temperature-gauge-on-dash-quit-working.html
-----------
Dodge neon gauges not working? http://technoanswers.blogspot.in/2012/02/dodge-neon-gauges-not-working.html

---------
Heater blows cold? http://schematicsdiagram.blogspot.in/2012/02/heater-blows-cold.html

----------
Heat blows cold on drivers side and hot on passenger side? http://schematicsdiagram.blogspot.com/2011/12/heat-blows-cold-on-drivers-side-and-hot.html

-----------
1992 Lexus LS400: Engine overheats, Antifreeze out of reservoir and heater Blows Cold Air? http://whatisbyme.blogspot.in/2012/05/1992-lexus-ls400-engine-overheats.html

-----------
These details will help.
Thanks.

Watch the temp gauge when the electric radiator fans come on. The temp sensor that controls when the fan comes on may be faulty.

if the gauge runs at this point under normal driving conditions consider it to be normal for that gauge,temperature gauges vary from vehicle to vehicle, if it fluctuates too much you may have a problem but if it is constant there is no need to worry.....hope this helps.....cheers.

First of all you have a bad heater core that needs to be replaced. Second you may have a bad temperature sensor. Make sure the radiator if full of water

I'm thinking the coolnat level is low, and this might be caused by a bad head gasket - At least $800 to fix - sorry.

MOST CARS TEMPERATURE GAUGE STAY IN MIDDLE.THATS NORMAL.BUT IF THE TEMPERATURE GAUGE STARTING CLIMBING TOWARD HOT WHILE DRIVING YOU GOT A PROBLEMS.THE THERMOSTAT STICKING CLOSE.LOW COOLANT OR RESTRICTED RADIATOR.POOR AIR FLOW.GRILLE RESTRICTED.