Outside Temp Display Accuracy?
03-28-2006, 05:11 PM
#1
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Outside Temp Display Accuracy?
The outside temperature display on my car does not seem to be consistently accurate. It often displays a temp several degrees lower that actual - sometimes as much as 20 degrees low.
Could this be a problem with the temp sensor - located in the driver side rearview mirror, I believe?
Does your exterior temp display accurately?
Could this be a problem with the temp sensor - located in the driver side rearview mirror, I believe?
Does your exterior temp display accurately?
03-28-2006, 05:16 PM
#2
Fleet of Foot
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Once mine sits in the sun, fuggeddaboutit!!! I've seen 125 F on mine in the summer. Seems fairly accurate at this time if the year though and no complaints at night.
03-28-2006, 05:31 PM
#6
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Originally Posted by Vilhuer
Isn't sensor in alternator cooling hose?
03-28-2006, 05:39 PM
#7
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I've noticed mine takes a while to find the right temp, but it usually is in the ball park. I thought it was because of my mirror condoms/bras.
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03-28-2006, 05:43 PM
#9
Did you know that the external temperature feature started in 1989 in conjunction with the digital dash? 
...
BTW..mine reads -40C all the time...and it has a new sensor..so likely a break in the wire through the door..
later,
Tom
89GT
...BTW..mine reads -40C all the time...and it has a new sensor..so likely a break in the wire through the door..
later,
Tom
89GT
03-28-2006, 06:05 PM
#11
I have had problems with my outside temperature probe, so I removed the mirror from my driver side to expose the temperature probe and I recorded the following write up in my work done history file, which you may find helpful
External Rear View Mirrors
Outside temperature probe reading 4 degrees centigrade low. Still have to find out whether adjustable via on-board computer or need to replace probe (Now know thanks to Jim Morehouse Technical Reference Books on CDs). Outside temperature probe locate in drivers side mirror. Removed mirror and then removed probe. Cleaned external surfaces of probe and connections and upon reassembling now reading correct temperature, or close enough. Side mirror reflector removal is quite difficult and there is a special procedure to remove.
Unfortunately the description in the Workshop Manuals for removing external mirrors on 1990 model cars is incorrect. The mirrors are removed by rotating the glass upwards as far as possible and between the mirror and the housing at the bottom is a serrated plastic ring which relates clockwise to unlock. It move around 3/8 inch and then mirror will be able to be removed. Be careful of the heating wires to the mirror. Once remove it will be noted that the mirror is held in place by four circular lugs and when the serrated ring is moved anti- clockwise into the locked position. The ring locks via a plastic section engaging a raised slot on the stator of the mirror holding ring.
I noted that the resistance ratios for the external temperature probe is shown in the Diagnosis of the Instrument Cluster Service Information Technical Manual ('89).
Tails 1990 928 S4 Auto
External Rear View Mirrors
Outside temperature probe reading 4 degrees centigrade low. Still have to find out whether adjustable via on-board computer or need to replace probe (Now know thanks to Jim Morehouse Technical Reference Books on CDs). Outside temperature probe locate in drivers side mirror. Removed mirror and then removed probe. Cleaned external surfaces of probe and connections and upon reassembling now reading correct temperature, or close enough. Side mirror reflector removal is quite difficult and there is a special procedure to remove.
Unfortunately the description in the Workshop Manuals for removing external mirrors on 1990 model cars is incorrect. The mirrors are removed by rotating the glass upwards as far as possible and between the mirror and the housing at the bottom is a serrated plastic ring which relates clockwise to unlock. It move around 3/8 inch and then mirror will be able to be removed. Be careful of the heating wires to the mirror. Once remove it will be noted that the mirror is held in place by four circular lugs and when the serrated ring is moved anti- clockwise into the locked position. The ring locks via a plastic section engaging a raised slot on the stator of the mirror holding ring.
I noted that the resistance ratios for the external temperature probe is shown in the Diagnosis of the Instrument Cluster Service Information Technical Manual ('89).
Tails 1990 928 S4 Auto
03-29-2006, 02:06 AM
#14
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Randy,
Mine regularly reports quite rediculous temperatures - 100F, 110F, 120F degrees.
Unfortunately for me its also quite accurate....
Except that the temperture inside the car is way hotter that that!
Alan
Mine regularly reports quite rediculous temperatures - 100F, 110F, 120F degrees.
Unfortunately for me its also quite accurate....
Except that the temperture inside the car is way hotter that that!
Alan
03-29-2006, 06:26 AM
#15
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Ah, I see. They used two different sensors because AC only needs on/off info if it's freezing or not (I think) while digital display needs temp data.
'90 GT friend bought and we brought from Germany last weekend seems to have accurate display. It was saying -7.5 Celcius when we drove GT and '88 S4 home last 80 miles from ferry in Finland. Luckily roads were mostly dry so no ice or snow on them. In Hamburg to Rostock autobahn temp was 10 to 15C warmer and raining constantly. Both times reading was accurate within Celsius or two at least.
'90 GT friend bought and we brought from Germany last weekend seems to have accurate display. It was saying -7.5 Celcius when we drove GT and '88 S4 home last 80 miles from ferry in Finland. Luckily roads were mostly dry so no ice or snow on them. In Hamburg to Rostock autobahn temp was 10 to 15C warmer and raining constantly. Both times reading was accurate within Celsius or two at least.