Outside temp wrong

[Yawnie'sPapa]

Funny thing about these - if you have a snow plow on the front, a low pressure area is created behind the plow. This pulls engine bay air forward across the sensor - causing it to read high. In some cases, 100 degrees or more. The engine will also run hotter because of that low pressure preventing air from moving back through the radiator.

Ask me how I know, and how I found the details on how these work. Yes, you have to drive 30 mpg or faster for something like a mile. I saw the FCA STAR docs and only recall the 30 mph part. A tech explained other things in detail when trying to help me with a solution.
The solution? Move the sensor or take the plow off when it's not needed.

81 degrees out with snow on the ground?

Or maybe you'd believe 99 degrees with snow (and that's down from the 101 it was when I pulled up to the light)

Anyway, because the temperature also controls the HVAC system, it's designed to not keep updating every second. They don't want wild fluctuations so they made it to "moderate" and use more average temperatures.
It was fun this past winter until we decided it was the snow plow causing it - NO heat in that truck because it thought it was anywhere from 80 to 101 degrees outside. It didn't matter what mode I put the heat in, it wouldn't warm that cabin up at all. My wife ran her side up to 75 and we were still feeling COLD air from the vents - dash and floor.

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[grimmjeeper]

This would explain why the external temp won't update while rock crawling. Every day this week in Moab doing trails, won't update until after done with the trail and get back up to highway speed rolling back to town.

Same thing happened to me all week too.

 

[gregeast]

The temp sensor als doesn't update unless you're driving 25 MPH or faster. So it can stay stuck if you're not going fast.

It starts with the reading when you first turn it on so if it's heat soaked you need to drive a bit for it to correct.

I find that it's not so far off if you're driving down the highway. In town it can be less accurate.

This explains a lot.

Seems like an odd choice for a vehicle designed to trundle along in low range at 3 mph for hours on end but it is consistent with our experience. I had begun to think it had something to do with cell reception, but this much more plausible.

 

[QC22]

This explains a lot.

Seems like an odd choice for a vehicle designed to trundle along in low range at 3 mph for hours on end but it is consistent with our experience. I had begun to think it had something to do with cell reception, but this much more plausible.

I was thinking cell as well. Two Jeeps together this last weekend, very remote, no signal. Stuck on 36 and 37 degrees respectively overnight. We were moving very slow for most of the next day. Ambient was 70s and our seat heaters were coming on every restart. Very annoying. Speed almost explains it, but the other Jeep updated much earlier than mine. Did not seem to coincide with a cell connection though, so speed may be it.

 

[Maverick909]

The temp today has not been above 41 (snow/sleet most of the day). When I got in the car this morning (it had been parked for about 15 hours in my detached, unheated, uninsulated garage) the car temp read 41 degrees (it was 34 outside). As I drove it, the temp eventually corrected itself. I parked it in my driveway outside for about 10 hours & when I got in tonight, it was 27 degrees but the car temp read 51. Again, as I drove it, the car temp corrected itself. It’s frustrating to me mostly because it’s obviously an issue for me & many other people but the dealership says it’s fine. And the feature of automatically warming the seat & steering wheel whenever the temp is below 40 is useless… but I’m paying for it anyway. Not cool.

youre seeing a last know heat soaked temp. all of my company silverados do the same thing

 

[gregeast]

While I agree that appears to be what's happening, what I don't get is why?

There is a temp sensor for outside temperature, why does it need to be going faster than 25 mph for some period of time in order to take a reading...especially in a Jeep!

 

[Ratbert]

While I agree that appears to be what's happening, what I don't get is why?

There is a temp sensor for outside temperature, why does it need to be going faster than 25 mph for some period of time in order to take a reading...especially in a Jeep!

If there's insufficient airflow then the perceived temperature would be significantly impacted by the ambient heat of the engine bay.

 

[QC22]

If there's insufficient airflow then the perceived temperature would be significantly impacted by the ambient heat of the engine bay.

Then Jeep needs to move the sensor to somewhere with less risk of heat soak and more airflow at low vehicle speeds. If you are out in the non-asphalt world for an extended period, you may not hit 25 MPH for hours (exactly what happened to me). This seems like a common usage of this vehicle and there should've been testing in conditions with different ambient temperatures that would expose this. This is particularly lazy and annoying to me. Makes the temperature info, and associated vehicle features (auto heat stuff) worse than useless. Worse because if there was no feature, and no indicated temperature, it would actually be better.

 

[Ratbert]

Then Jeep needs to move the sensor to somewhere with less risk of heat soak and more airflow at low vehicle speeds. If you are out in the non-asphalt world for an extended period, you may not hit 25 MPH for hours (exactly what happened to me). This seems like a common usage of this vehicle and there should've been testing in conditions with different ambient temperatures that would expose this. This is particularly lazy and annoying to me. Makes the temperature info, and associated vehicle features (auto heat stuff) worse than useless. Worse because if there was no feature, and no indicated temperature, it would actually be better.

Yeah, I guess it might be better if they simply disabled it when it's not updating. Maybe you can get Tazer to implement that.

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