Toyota Camry 1990 Temp gauge on high

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In all my time is founder of Virtual Mechanic the following issue with a Toyota Camy tempreture gauge reading high after a short drive would make most people think the repair may lead the a costly repair.
But I cannot take the credit for a very good outcome proving that the real problem was a poor earth connection.
It was Neil Gray of Brisbane that found this problem by going to the trouble of locating a vital earth connection that was required to complete the tempreture sender to guage circuit.

This issue with the Toyota Camry may cost many motorists a costly mistake if not diagnosed correctly, to all who read this and rectify the problem at minimal cost will be gratful to Neil Gray.

May I add that all Car manufactures, Toyota, Holden, Ford, Nissan, Mitsu, etc should be offering and sending data in the form workshop manuals free of charge to the Virtual Mechanic to help prevent costly mistakes at any workshop or service centre.

I thank Neil Gray for going to the trouble of locating the cause of the high tempreture reading leading to a poor earth connection secured at the engine exhaust manifold.

Written by Darren Gow-Brown

Name Neil Gray
State & Suburb Brisbane QLD>

Type of Vehicle Toyota
Model Camry
Month/Year 12/1990
Kms 120,000
Problem This is a fuel gauge problem. I have replaced the sensor and the gauge.
The gauge goes to full scale after a short time(1min)
I’ve had the coolant temp checked its O.K
The fans come on O.K if I”m stuck in traffic for a long time and go off when i get rolling.
Please help as motorama don’t know what i’m talking about
ta neil

Your Question does not make sense

No thats because im an idiot Its The TEMPERATURE GAUGE THAT GOES FULL SCALE
Thanks for your patience Darren
Neil Gray

Ok Neil,
Now the temperature gauge goes to full in one minute this sounds like its either a faulty gauge or something causing the coolant to rise in temperature
When the cooling fans switch on can you count how many minutes or seconds the thermo fans stay on

i’ve replaced the gauge
the fans stay on  for about 2mins when i get moving.

Darren wrote:
@ minutes is far to long if we use an example of a standard passenger vehicle in normal operating condition its around 40 seconds
therefore you have a cooling system issue

Could it be the thermostat?

Darren wrote:
Yes the best way to measure the thermostat is with the engine at normal operating temp and the engine switched off feel the upper hose and the lower radiator hose and check for a difference in temp
Neil you may also have a blocked radiator to give the same result

hi darren,
thanks for the help..i’ll get back to you when it stops raining and i can look at the problem.
thanks again

Hi Darren,

I have replaced temp meter
I have replaced the thermostat
I originally replaced the sensor

The car still runs O.K.
The meter still goes to full scale
The coolant seems to be circulating O.K.

Could it be:-
(1)  Water pump not working efficiently?
(2)  Faulty sensor sold to me new ?
(3) Meter Mother Board in dash?

I am about to attack the horrible thing with a sledge hammer

Hi Darren,


Having looked at the electrical wiring diagram I thought it could be that the earth on B5 of the combination meter plug was missing.
This earth comes from a point on the engine manifold at the rear of the engine.

Happy days

Thanks for your efforts on my behalf on this very obscure problem.
I thought you might like feedback on the fix

Hi Darren,
I have added a note to diagram in magenta
Hope this is satisfactory



Hi Neil

I have published your efforts, and hope many people will read this an not make a costly mistake of a Head repair……..


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