E30 325i Outside temp

My 1990 325 has a factory outside temperature display/date/digital clock in
place of the analogue clock or OBC. It has always been highly reliable and
accurate since I bought the car 17 years ago but recently it is showing
approx 10C below the actual temp. Anyone know where the sensor is and if
they are prone to any faults of this kind?

> My 1990 325 has a factory outside temperature display/date/digital clock in
> place of the analogue clock or OBC. It has always been highly reliable and
> accurate since I bought the car 17 years ago but recently it is showing
> approx 10C below the actual temp. Anyone know where the sensor is and if
> they are prone to any faults of this kind?

It's in the front brake duct, behind the spoiler. When they fail you
normally just get a constant very low reading, such as -37C.

--
Who needs a life when you've got Unix? :-)
Email: , John G.Burns B.Eng, Bonny Scotland
Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html
www.Strathspey.co.uk - Quality Binoculars at a Sensible price

On May 31, 5:17 pm, John Burns > wrote:
> > My 1990 325 has a factory outside temperature display/date/digital clock in
> > place of the analogue clock or OBC. It has always been highly reliable and
> > accurate since I bought the car 17 years ago but recently it is showing
> > approx 10C below the actual temp. Anyone know where the sensor is and if
> > they are prone to any faults of this kind?
>
> It's in the front brake duct, behind the spoiler. When they fail you
> normally just get a constant very low reading, such as -37C.

Burns is right - and it is not uncommon for the sensor to fail. Used
ones go for $10-$20 on ebay.
--
C.R. Krieger
(Been there; done that)

"John Burns" > wrote in message
...
>> My 1990 325 has a factory outside temperature display/date/digital clock
>> in
>> place of the analogue clock or OBC. It has always been highly reliable
>> and
>> accurate since I bought the car 17 years ago but recently it is showing
>> approx 10C below the actual temp. Anyone know where the sensor is and if
>> they are prone to any faults of this kind?
>
> It's in the front brake duct, behind the spoiler. When they fail you
> normally just get a constant very low reading, such as -37C.

In that case it has not failed - simply reads low. Thanks for the info about
the location - I'll check its condition.

David

"David Haggas" > wrote in message
...
>
> "John Burns" > wrote in message
> ...
>>> My 1990 325 has a factory outside temperature display/date/digital clock
>>> in
>>> place of the analogue clock or OBC. It has always been highly reliable
>>> and
>>> accurate since I bought the car 17 years ago but recently it is showing
>>> approx 10C below the actual temp. Anyone know where the sensor is and if
>>> they are prone to any faults of this kind?
>>
>> It's in the front brake duct, behind the spoiler. When they fail you
>> normally just get a constant very low reading, such as -37C.
>
> In that case it has not failed - simply reads low. Thanks for the info
> about the location - I'll check its condition.
>
> David


It's either a thermistor or a thermocouple (the former is my guess), and
these devices can fail in such a fashion that the resistance they attain at
a certain temp is incorrect. The circuits they are in are prone to reacting
to corroded connections too. As a general rule, the resistance they have is
higher at cold temperatures, so corrosion on the contacts can lead to lower
readings on the display.

A thermocouple and a thermistor behave similarly, although they achieve
results in a different manner. I do not think it is important which device
is used in your car. I think your problem is either a poor connection due to
the location of the connector, or the device itself is failing. As was
pointed out earlier, they generally are a go-no-go kind of device, so paly
with the connector for a few minutes, and replace the device next week if it
still does not read correctly.

"Jeff Strickland" > wrote in message
news:4Bg8i.318$fX4.235@trndny03...
>
> It's either a thermistor or a thermocouple (the former is my guess), and
> these devices can fail in such a fashion that the resistance they attain
> at a certain temp is incorrect. The circuits they are in are prone to
> reacting to corroded connections too. As a general rule, the resistance
> they have is higher at cold temperatures, so corrosion on the contacts can
> lead to lower readings on the display.
>
> A thermocouple and a thermistor behave similarly, although they achieve
> results in a different manner. I do not think it is important which device
> is used in your car. I think your problem is either a poor connection due
> to the location of the connector, or the device itself is failing. As was
> pointed out earlier, they generally are a go-no-go kind of device, so paly
> with the connector for a few minutes, and replace the device next week if
> it still does not read correctly.

Thankyou for that Jeff. Todays temperature was around 23 and the reading was
8.5 which points to the above. Investigations pending.

"John Burns" > wrote in message
...
>> My 1990 325 has a factory outside temperature display/date/digital clock
>> in
>> place of the analogue clock or OBC. It has always been highly reliable
>> and
>> accurate since I bought the car 17 years ago but recently it is showing
>> approx 10C below the actual temp. Anyone know where the sensor is and if
>> they are prone to any faults of this kind?
>
> It's in the front brake duct, behind the spoiler. When they fail you
> normally just get a constant very low reading, such as -37C.
>
> --
> Who needs a life when you've got Unix? :-)
> Email: , John G.Burns B.Eng, Bonny Scotland
> Web : http://www.unixnerd.demon.co.uk - The Ultimate BMW Homepage!
> Need Sun or HP Unix kit? http://www.unixnerd.demon.co.uk/unix.html
> www.Strathspey.co.uk - Quality Binoculars at a Sensible price

On the older ones it was a constant high of 84F / 29 or 30C.