USB and CarPlay doesn’t work when hot outside.

[theblet]

I don’t think it’s tied to the radios temp sensor either, from my findings. It didn’t work at 93, but worked at 96 after I turned the truck off for 10 min.

 

[Shots]

Hmm. I guess that fits more with the tpms scenario or a timer than the independent sensor. I wonder then if it has to be below xx° for a given time, and/or an ignition cycle before it will turn back on.

 

[Dmalonecentral]

I don’t think it’s tied to the radios temp sensor either, from my findings. It didn’t work at 93, but worked at 96 after I turned the truck off for 10 min.

From everyone’s (including mine) anecdotal experience, while driving with air on max it’s almost always 30 minutes and it will come back on. I sat in my truck running with the AC full blast for an hour and couldn’t get it to turn back on. If ran for a little while and then turning off the car long enough for the radio to actually power off (maybe USB as well) it will usually come back as long as the truck isn’t baking in the sun. What’s the power down cycle on the USB after shut off, like 1 hour, or 30 minutes?

 

[Shots]

Yeah that sounds right. I forgot the hub stayed on for a while after the truck is off. From the sounds of it, I wouldn't be surprised if that power down was 30 minutes.
So you'd need a 30 minute reset after you get the temp down? That sucks.

 

[theblet]

I find the same thing, but o don’t have to power down for 30 min. 10 min usually does it @RamCares hasn't responded yet

 

[Dmalonecentral]

Yeah that sounds right. I forgot the hub stayed on for a while after the truck is off. From the sounds of it, I wouldn't be surprised if that power down was 30 minutes.
So you'd need a 30 minute reset after you get the temp down? That sucks.

Well evidently it’s one hour so not sure about the correlation there. Of note today though, it got up to 108° or so and I made multiple trips throughout the day so I don’t think the USB was every actually powered off and the cabin never got hot enough for the issue to occur. Very strange.

 

[Dmalonecentral]

I find the same thing, but o don’t have to power down for 30 min. 10 min usually does it @RamCares hasn't responded yet

@theblet Since you are experiencing the same issue I had another thread going asking if it was possible to bypass the media hub and go directly to the head unit for CarPlay. According to one guy you cannot but I noted some observations over there if you want to take a look. I am now determined to figure this out because it absolutely ridiculous that we can’t use this feature in the summer.

Bypass Media Hub (Fixed Link, I think)

Bypass Media Hub

I was looking online and it appears the connectors on the back of the Media Hub are standard Mini USB-B connectors. Does anyone know if it’s possible to just bypass the media hub and plug directly into the Head Unit for CarPlay since the media hub quits working when sitting in temps more than...

5thgenrams.com

 

[swizlstik]

I’m in the Phoenix area and I experience this issue all the time too. Mine is the same as everyone else has explained, CarPlay doesn’t work when the truck is first started but if it’s turned off after getting cooled down, it will work. Very frustrating!!

 

[Dmalonecentral]

Found this article in PTC Thermistors. Basically it’s a heat sensitive resistor this limits current as the temperature rises. A common application is USB. This could explain the behavior we are seeing but it seems that they could possibly be a bad batch because according to a paper I found that was put out by Texas Instruments the operating temperature In Automotive grade applications should be up to 125°C or 257°F.

https://product.tdk.com/en/techlibrary/applicationnote/howto_ptc-limiter.html

https://www.ti.com/lit/ds/symlink/tpd3s714-q1.pdf?ts=1655347062122&ref_url=https%253A%252F%252Fwww.google.com%252F

What say you @RamCares?

 

[Dmalonecentral]

More good information from a local Microchip about Media Hubs.

USB Media Hub | Microchip Technology

Note the Temperature Sensors section.

 

[theblet]

@theblet Since you are experiencing the same issue I had another thread going asking if it was possible to bypass the media hub and go directly to the head unit for CarPlay. According to one guy you cannot but I noted some observations over there if you want to take a look. I am now determined to figure this out because it absolutely ridiculous that we can’t use this feature in the summer.

Bypass Media Hub (Fixed Link, I think)

Bypass Media Hub

I was looking online and it appears the connectors on the back of the Media Hub are standard Mini USB-B connectors. Does anyone know if it’s possible to just bypass the media hub and plug directly into the Head Unit for CarPlay since the media hub quits working when sitting in temps more than...

5thgenrams.com

Thanks for this. Do it looks like if you bypass the hub, you would only get power. I wish someone would actually tell us what the technical explanation is, what are the thresholds, and what values allow it to function again.

 

[Shots]

.... I wish someone would actually tell us what the technical explanation is, what are the thresholds, and what values allow it to function again.

I'm not experiencing this problem but this seems like a simple enough request.
Even if there isn't a solution, they could at least tell you how/when it's supposed to work.

 

[Lpsouth1978]

Weird, I also live in Phoenix and I have never had this issue. My RAM is parked outside everyday and temps inside the truck get VERY hot.

 

[Dmalonecentral]

Weird, I also live in Phoenix and I have never had this issue. My RAM is parked outside everyday and temps inside the truck get VERY hot.

This makes me think there is a bad batch of resistors in the media hubs.

 

[Dmalonecentral]

This makes me think there is a bad batch of resistors in the media hubs.

I see you have 2021. Mine is a 2019. They could have fixed it in the later versions.

 

[swizlstik]

I see you have 2021. Mine is a 2019. They could have fixed it in the later versions.

Mine is a 2019 as well.

 

[theblet]

mine too

 

[Dmalonecentral]

Just want to add that not sure exactly what causes the power to come back to the media hub during the course of normal driving when the cabin temp and ultimately the temp of the thermistor come back down to safe operating temps but can confirm that pulling the F43 fuse and putting it back in did work immediately for me. Temp was in the 110-112 range today. Auto started the truck about 10 minutes before we left, drove about 5 miles. CarPlay not working this whole time. Got to our destination and pulled the fuse for a few seconds and reinserted and BAM, CarPlay started working immediately. This isn’t going to help much if you are driving as you have to pull the panel below the steering wheel to access the fuse and it’s hard to get to even after you do that but I think it’s worth noting that manually cutting power and turning it back on will bring CarPlay back if the temp is below whatever threshold the Thermistor can handle. I am considering adding a Toggle switch to that fuse location to be able to do this while driving. Also note that this fuse also powers the OBD port and the CD player.

 

[theblet]

Just want to add that not sure exactly what causes the power to come back to the media hub during the course of normal driving when the cabin temp and ultimately the temp of the thermistor come back down to safe operating temps but can confirm that pulling the F44 fuse and putting it back in did work immediately for me. Temp was in the 110-112 range today. Auto started the truck about 10 minutes before we left, drove about 5 miles. CarPlay not working this whole time. Got to our destination and pulled the fuse for a few seconds and reinserted and BAM, CarPlay started working immediately. This isn’t going to help much if you are driving as you have to pull the panel below the steering wheel to access the fuse and it’s hard to get to even after you do that but I think it’s worth noting that manually cutting power and turning it back on will bring CarPlay back if the temp is below whatever threshold the Thermistor can handle. I am considering adding a Toggle switch to that fuse location to be able to do this while driving. Also note that this fuse also powers the OBD port and the CD player.

Interesting. I wish we know what the threshold is. Was there a redesign on this hub that would fix the problem? I am expecting a call from FCA, and will let you know what they say.

On another note, anyone know how to replace it or get it out? What if the thermistor is replaced with a regular resistor?

 

[Dmalonecentral]

Interesting. I wish we know what the threshold is. Was there a redesign on this hub that would fix the problem? I am expecting a call from FCA, and will let you know what they say.

On another note, anyone know how to replace it or get it out? What if the thermistor is replaced with a regular resistor?

According to the part number there have been 5 revisions but the paperwork for the last time mine was replaced shows this latest revision part number (Sept 2021). I went ahead and ordered one from Mopar anyway and will verify the part numbers when I get it.

Part Number: 68272254AE
Supersession(s): 68272254AA; 68272254AB; 68272254AC; 68272254AD