Temp gauge troubleshooting?

[CarGuy]

Okay – I’ll try and keep this short. When I bought my SVO, I noticed the temp gauge read really low. Actually, you wouldn’t even think it was working unless you sat in some traffic for a while and the needle would move almost close to the “N” at the beginning of the gauge. Is it just a simple sensor that needs to be replaced or is it going to take some electrical troubleshooting to figure out.

Thanks

[kiwi]

temp Gauge....

I have the same problem.......Ford says its the gauge & I have a new one in the garage......I can't give you specifics on checking the gauge, but I'm sure it's in my manual (at home) if it operates on ohms (grounding) or what.....I will look it up tonite!

[CarGuy]

If it’s the gauge – then I could replace it while I have the dash apart Are there any tests to see whether it’s the gauge, sensor, or wiring?

[GAboySVO]

The first thing you want to confirm is whether the guage is acuate or not. If the previous owner has taken the thermostat out, then it probably wouldn't heat up until you were in stop and go traffice with the AC on.

You might try: Let the car idle with the AC on. Even with the fan on this is the quickest way I have found of warming the engine quickly. Actually measure the temp of the fluid in the radiator. See how it jibes roughly with the guage. The idle temp after warming should be ~180*-200* or ~ just to the right of vertical on the guage.

There is also a voltage regulator behind the instrument cluster that has been known to crap out and make the guages do funny things.

Check the wires and connector for the temp sending unit for corrosion and or breakage. Corrosion can increase the resistance and affect the voltage.

And lastly, replace the sending unit.

[kiwi]

Re: CarGuy

Checked Factory Shop Manual......Do not apply 12 volts or direct ground to temp gauge sending wire.....Using a 10 & 73 ohm resistor in between same wire & ground to see if gauge reads "H" & "C" respectively with key "ON"......If gauge passes, replace sender....If gauge does not pass: replace the IVR (common regulated voltage) and retest:::note- several of the gauges will fluctuate if this is bad.....If gauge still reads wrong during resistor testing, then replace the gauge......

[CarGuy]

Man - those instructions are in my Haynes book too doh! I was looking in the wrong chapter. Mine states if the IVR is possibly bad, then all gauges would read erratically. But anyway - it gives the same steps for using the resistors.

Thanks for your help Kiwi - I'll put mine on the test and see what it shows.

Here is my best guess for the color codes on the two resistors if anyone is interested:

10-ohm Brown(1), Black(0), Black(X1), Gold(5% Tolerance)

73-ohm Violet(7), Orange(3), Black(X1), Gold(5% Tolerance)

[kiwi]

Re: CarGuy

.......there is/was some fancy tool mentioned also with "settings".....I have not heard of it....

[CarGuy]

Just an update: Resistor test showed gauge worked fine. I replaced the temp switch in the block, and it reads much better now.

BTW - I noticed the switch was like a copper or brass type deal. I used some anti-seize on the threads - Is there anything else I should of used with that kind of stuff?

Thanks again

[Eyelawdoc]

Anti-sieze is the correct stuff to use!