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Skyvisions, ASE Certified Technician
Category: Toyota
Satisfied Customers: 14324
Experience:  Toyota Master Diagnostic
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TOYOTA COROLLA: temp gauge..radiator..the instrument panel..alternator

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My TOYOTA COROLLA 1990 has both FUEL and WATER TEMP gauges going up further than they normally do.
The tank is almost empty but the fuel gauge says half full. The water temp gauge got off the top of the scale when in traffic but yet no steam out of the radiator.
Curious thing is no warm air from the heater, but the engine radiator is very warm.
This has just happened.
I suspect some sort of voltage regulator in the instrument panel that is now supllying too much current to the two meters.
Measured alternator voltage. 14.2 - slighly high too.

Is there a regulator inside the instrument panel (- before I take it out) ?

Any thoughts ?

Thank you for choosing JustAnswer and allowing me to help you resolve your Toyota questions!


The last time I had this happen I had to replace the gage unit as an assembly to fix it. If you are certain the temp is not hot and the coolant level is full and circulating the issue will be related to the unit in the combination meter. If you can post a picture of the gages I can tell if it is the same style. The only other test you can do is the resistance test of the sending unit in the tank and the temp sensor in the engine. 14.2 volts is normal.



Customer: replied 6 years ago.
My problem is that both gauges are high but both have separate earths.
The only thing that is common is the 14v supply and the instrument panel circuitry.

Basic. 1.3 liter engine think its a E3 or something.

The instrument panel has MODEL E29 written near the bottom of the SPEEDO.
Gauges panel has door/heat-rear-window lights on the left
Seedo on left-centre
IGN, OIL, BRK lights in a square
FUEL and TEMP on right
RED-FOG light on far right side.

I'm happy that you've confirmed the supply voltage, so it looks like the instrument panel is coming out next !!

Do I "pay you now" or whats the procedure ???

You can accept when you are satisfied that the help I have provided was useful. If you can get the Vehicle Identification Number I may be able to look up some other info. What country are you from? .




Edited by Skyvisions on 4/6/2010 at 9:36 PM EST
Customer: replied 6 years ago.
sorry for delay...its dark here in Ireland had to go find torch.
I'm good at most things...but seeing in the dark isnt one of them.

Thanks for all the info so far.
I owe you a few more 'dollars' by now.
Let me know how to do that.

VEHICLE ID IS JT1EOEE9000256425 MAYBE JT1E0EE9000256425


Rt hand drive? Auto Trans? EFI 2EE engine?


No rush it just kept popping up on my end saying you where requesting me.



Customer: replied 6 years ago.
Oh yes..right hand drive. Manual trans.

As for engine I dont know.
Its a 1296cc 4 cylinder
- maybe a sticker that said E12 on the rocker-cover one time - just dont know now

That is a different combination meter then what is used here in the USA. If they both started acting up at the same time I would check the common earth points. then check the resistance of the sending units and make sure they are in line. My wiring info is limited on the world market Toyotas. If you would like I can transfer this to the UK category.



Skyvisions and 3 other Toyota Specialists are ready to help you
Customer: replied 6 years ago.
Nahhhh relax... you've done enough for now.


I'll pull the dashboard apart and inspect.
I have a HAYNES manual (not as in-depth as I hoped) here and from what it says, the
two meters are on separate grounds with common supply so it has to be inside the
instrument panel.

OK - listen man... thanks for your help.
I'll call it closed.
Thank *YOU*

You are welcome. If you need anything or a second opinion let me know.



Customer: replied 6 years ago.

Hello there..

See PDF file for solution to this in pictures.

Nicely done, makes perfect sense, great pictures, good job.