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Thermometer readings a little off?


STS Scott

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The Outside Temp. reading seems to be a little inaccurate lately.

The temp is always higher than wht I believe it should be, such as last night, I drove by one of those information signs with the time, temp, advertizing, etc.

It indicated 31 degrees, where as the STS indicated 38.

Now I know sitting still the engine heat would effect an accurate reading, but this was after driving for a while, and not the first time I have questioned it's acuracy.

Is there a way to recalibrate it, or should I just stick a post-IT to the dash that says "take away five+" so I never forget?

Thanks!

" ...'took my Cobra down t' the track, hitched to the back o' my Cadillac..."

- Jan & Dean, 'hey little cobra'

Scott

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I do not believe it can be recalibrated. However, the service manual should have a chart to compare resistence values that equate to certain tempuratures so you can check it's accuracy. I would trust it much more than any of the time/temp signs I've ever seen. They are notoriously wrong.

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The onboard temp display is far more accurate than some temperature sign - there is an algorithim to negate the effects of engine heat - the displayed temp is not allowed to rise unless the car has been travelling X mph or faster for x minutes.

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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Mine was also out a few degrees.

I replaced the sensor and it was still off by the same amount.

Having the temperature off by a few degrees was annoying and somewhat dangerous.

Living on the East coast in snow country means huge swings of temperature in the Winter.

We could have a + temp day and rain and then the temp could drop quickly.

While driving if the road/air is wet and above freezing, it's nice to know when the air temperature drops below freezing.

The road temperature will drop below freezing soon after. Wet road + freezing = not good.

So.... I constructed a calibrating device to bring the sensor to an accurate reading.

It's just a variable resistor mounted in series with the sensor under the hood.

A house thermometer and a few adjustments later and I had an accurate outside reading.

I mounted the resistor in a weather tight container just behind the sensor.

(Container/resistor plugs between the sensor and harness)

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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....

So.... I constructed a calibrating device to bring the sensor to an accurate reading.

It's just a variable resistor mounted in series with the sensor under the hood.

A house thermometer and a few adjustments later and I had an accurate outside reading.....

Barry

Barry:

Is the correction linear?

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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....

So.... I constructed a calibrating device to bring the sensor to an accurate reading.

It's just a variable resistor mounted in series with the sensor under the hood.

A house thermometer and a few adjustments later and I had an accurate outside reading.....

Barry

Barry:

Is the correction linear?

Yes, it's linear.

I've checked it against my house thermometer from approx. -18C (0F) to +30 C (86F).

When arriving home I would note the reading on the car and then check it against the house thermometer. (Digital)

I don't remember the value of the resistor, however it was cheap at Radio Shack.

Barry

2008 STS V8
2016 Colorado Z71
1970 Corvette LT-1 Coupe

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That is a really clever idea. Barry!

I'll consider doing that, as I know what you mean with the cold temps fluctuating, here in Canada!

I know Radio Shack here in Canada does not carry resistors anymore, but there is a TV repair place locally that still does, so I should be set.

Thanks for the added input!

" ...'took my Cobra down t' the track, hitched to the back o' my Cadillac..."

- Jan & Dean, 'hey little cobra'

Scott

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