exterior temp reading wrong after replacement of display - PeachParts Mercedes-Benz Forum

land sea air · #1 07-18-2007, 07:53 PM

So here's my problem. I have a 1988 300E with the usual half broken exterior temperature display so I ordered a used one. Upon installation of the unit it is now reading about somewhere around 40 degrees to low of a temperature. Normally I would just assume it's the sensor reading wrong but before replacement the first half of the display would still be reading at least withing 10 degrees (ie it would be 95 outside and the display would read 9--- since the other half is broken) is there some sort of calibration I can do or maybe I have the wrong display? It looked slightly different in some minor ways but the part number was similar and it had the same plug as well as fitting with no problems...
Any ideas on this one?

okc329 · #2 07-18-2007, 07:59 PM

you got a display set up for centigrade degrees not Farenheit degrees. I don't know what can be done if that's the case.

land sea air · #3 07-19-2007, 12:49 AM

the display is reading in degrees Fahrenheit, at lease visibly. plus it usually reads in the mid 50s currently isn't that a little hot?

david s poole · #4 07-19-2007, 10:41 AM

did you replace the sensor wire that goes from the back of the front lic plate to the display?

land sea air · #5 07-19-2007, 08:14 PM

No, I figured since it was reading at least close to right (within 10 degrees) before I replaced the display that it wasn't bad...

EliotW · #6 07-19-2007, 09:17 PM

I hope you'll excuse me for piggy backing you topic John as its related.

Damage to the cable would induce error into the reading rather than causing it to cease function? I'll admit I don't know how the sensor works at all.

land sea air · #7 07-20-2007, 07:34 AM

Quote:

Originally Posted by EliotW

I hope you'll excuse me for piggy backing you topic John as its related.

Damage to the cable would induce error into the reading rather than causing it to cease function? I'll admit I don't know how the sensor works at all.

yes as far as I know from reading other threads a faulty sensor/sensor wire can cause the display to read a temperature that is way off. I don't know if it usually means there is damage or if it just "goes bad" after 20 years. However in my case I do not believe that the sensor is the problem since it appeared to be reading correctly before replacement of the display

mespe · #8 07-21-2007, 11:29 AM

sounds like you got a bad display,,, my daughters 190e the outside temp worked fine ,,, until she hooked the bumper and ripped the thermocouple in half,,, now it reads -36F all the time

land sea air · #9 07-21-2007, 11:09 PM

well I guess I'll call the guy and see if he can refund me or send me one that is guaranteed to work... I always thought that as long as it wasn't cracked there wasn't anything that could go wrong with the displays