Outdoor Temp indicator gets stuck at same temp

[II kings 9:20]

More knee slappers (but this is not funny) from DC, mine had the same problem and was flashed to v 3.61 last year and with few exceptions has been accurate. I thought all this stuff had been figured out by now. How hard can it be to have a reasonably accurate thermometer? Now I see why some SRT8s are bending pushrods. (ooh, low blow, I could not resist).

[300C_AWD]

Use the steering wheel Easter egg trick posted somewhere on this site. I don't have my car here but I'm pretty sure it will show you the average and raw temp. The raw temp is updated continually.

[jlohrenz]

Yep I know that. Just can't quite figure out where the AVG should be set at to get a more accurate temp.

[BobF]

Originally Posted by jlohrenz

Yep I know that. Just can't quite figure out where the AVG should be set at to get a more accurate temp.

I have a 2006 300C. The outside temp always reads about 8-10°F. hotter than it should be. Per the manual the temp sensor is a variable resistor with a resistance of 336 kohms at -40°F. and a resistance of 2.488 kohms at 130°F. Using those values I calculated the following resistances at various temperatures:

Temp. (°F) Resistance (kohms)
50 158.9
60 139.3
70 119.7
80 100.05
90 80.43
100 60.82

It should be a simple matter of removing the connector from the sensor and measuring the sensor resistance at a known temperature. If the resistance is correct the sensor is OK and there is a problem with the method that Chrysler uses to calculate the temp. I'd try it on my car but have no way to get under there to disconnect it due to my disabilities. I don't know what the EVIC raw and average readings are on my car. I'll check it the next time I have time to see what the values are. Regards, Bob.

[joey]

My C always took awhile to finally start to show a reasonably close temp. After a year of ownership, I had the TSB to fix the problem. Since the TSB, I actually think the temp readings are worse than before. The temps still are slow to move, and when they do they seem to be about 10 degrees too high. Before the TSB the temps seemed to be around 3-5 degrees off.

[BobF]

Originally Posted by joey

My C always took awhile to finally start to show a reasonably close temp. After a year of ownership, I had the TSB to fix the problem. Since the TSB, I actually think the temp readings are worse than before. The temps still are slow to move, and when they do they seem to be about 10 degrees too high. Before the TSB the temps seemed to be around 3-5 degrees off.

The manual says with temperatures of 130°F. or above, or the sensor shorted, it should read 130°F. and with temperatures of -40°F. or below, or the sensor open, it should read -40°F. If these two checks are done, and it does not read right, there is a problem with the temperature measuring system and the technician at the dealer should be able to find that out quickly. I am going to go into the dealer as soon as time allows and have them check it and fix it, if possible. Regards, Bob.

[jaydee]

Originally Posted by BobF

The manual says with temperatures of 130°F. or above, or the sensor shorted, it should read 130°F. and with temperatures of -40°F. or below, or the sensor open, it should read -40°F. If these two checks are done, and it does not read right, there is a problem with the temperature measuring system and the technician at the dealer should be able to find that out quickly. I am going to go into the dealer as soon as time allows and have them check it and fix it, if possible. Regards, Bob.

This (open circuit/close circuit) testing seems to be a more logical approach than to try and figure out resistance values of intermediate temperatures since the response curve of the thermistor sensor may not be linear..

Jaydee

[BobF]

Originally Posted by jaydee

This (open circuit/close circuit) testing seems to be a more logical approach than to try and figure out resistance values of intermediate temperatures since the response curve of the thermistor sensor may not be linear..

Jaydee

Thanks. You are right. The output may be non-linear. Regards, Bob.