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Discussion Starter #1
Our Boxster S was equipped with PCM 3.1, Bose & navigation. We had intermittent issues with the PCM since we first got her but the issues had been few and far apart. There were a few times where the screen was completely black even though the PCM was otherwise functional with music playing. Sometimes the currently playing music info was missing on the BT-Aux screen. For a while now, however, it had been constantly dropping bluetooth connectivity to my wife's phone which was a major issue for her since she relies on bluetooth both for audio streaming and navigation voice prompts when going to clients.

Our dealer offered to replace the PCM for about $3K with labor. We decided to shop around and for under $2K we were able to get a Kenwood DMX906S with wireless Carplay, the requisite MOST-HUR 31 to interface with the factory Bose amp, a rearview camera and labor. Our PCM was limited to sofware 3.4.1 (I think but definitely not capable of 4.x) so options were very limited and/or pricey like the $1,600 NAV-TV modification service.

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For those curious, the gauge cluster screen will lose the functionality of the phone, audio, map & navigation screens. All the other screens remain functional. The audio screen displays NAVTV HUR and can be used to adjust settings of the MOST-HUR 31 if you have steering wheel controls. The process is a bit different if you do not.
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The car functions that were available via the PCM are not available but we never used those. I don't recall if there was other functionality available via the PCM that I have not covered but if there is, we didn't really use it either.

There are a couple of issues that need to resolved. For wireless Carplay, connection of the speed sensor wire is required. The shop claimed that our 981 didn't have one but they may have just not known where to find it. I haven't had much luck searching online so I am looking to install the Kenwood KNA-SPM100 OBD2 adapter myself. The interesting thing is that if an iPhone is connected for wired Carplay that it will continue to work wireless when disconnected so I guess that will be a short term workaround. The gain on the MOST-HUR 31 seems to have been set too high as there is a constant low level hiss and the volume on the head unit doesn't have to be turned up much before it's way too loud. I'll lower the gain when wiring the KNA-SPM100 as we don't have a multifunction steering wheel so making the adjustment involves pressing a button in the MOST-HUR 31.
 

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Thanks for the details of your replacement, I am sure more may follow this path if their PCM fails...
 

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Thanks! I'm planning to do the same in very near future. Completely throwing out Porsche PCM seem to be the only way to upgrade.

What to you mean by speed sensor wire? What does it do exactly? I remember smth like that necessary in one of my previous cars/subaru , but don't remember the solution, just know it exists.
 

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Discussion Starter #4
It’s also called the VSS or speedometer wire and provides pulses that indicate the vehicle’s speed. I did find one post on Planet-9 indicating that it might be available via the ABS module in the frunk.
 

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I did this with my 2015 Boxster early summer with a Pioneer unit that has wireless CarPlay. It has worked well, but loses audio every 2 months or so, and I’ve gotten used to the routine of temporarily unplugging the MOST HUR unit, tucked in the passenger footwell, to reset it. Then all is well again. My installer spoke with a tech, and my understanding is that turning the car on can disrupt the unit due to initial fluctuations in voltage. The suggested solution was a device to delay activation of the unit for 30 seconds, but I didn’t like that idea and haven’t done that.
 

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I did this with my 2015 Boxster early summer with a Pioneer unit that has wireless CarPlay. It has worked well, but loses audio every 2 months or so, and I’ve gotten used to the routine of temporarily unplugging the MOST HUR unit, tucked in the passenger footwell, to reset it. Then all is well again. My installer spoke with a tech, and my understanding is that turning the car on can disrupt the unit due to initial fluctuations in voltage. The suggested solution was a device to delay activation of the unit for 30 seconds, but I didn’t like that idea and haven’t done that.
Ugg. I have the same issue. Glad to know it's not just me. I ended up wiring in a switch in my glove box that turns power off/on to the MOST unit.
 

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Do you happen to know where your installer found the speed sensor wire?
I don't believe my speed sensor wire was hooked-up. I'm curious why that would be needed. The phone can provide speed info via gps. I find my gps speed is just 1mph different than the car's speedometer.
 

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Ugg. I have the same issue. Glad to know it's not just me. I ended up wiring in a switch in my glove box that turns power off/on to the MOST unit.
Yeah, it's unfortunate. I'm hardly knowledgeable regarding electronics, but it seems to me the MOST unit could protect against that problem with a capacitor or something. Your solution makes sense.
 

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Usually car entertainment units require speed wire to NOT let play videos when the car is moving. So the question usually is how to disable it, not how to hook it up :)
 

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Discussion Starter #11
Yeah, it's not for GPS. The DMX906S actually has its own GPS antenna even though it has no navigation features. As I understand it, it's there under the assumption that those using wireless Carplay may leave the phone in a location (e.g in a bag, etc) where the phone's GPS receiver may not work as well. No idea why the speed sensor wire is generally required.

That said, Kenwood release a firmware update for the DMX906S back in October that eliminates the need for the speed sensor wire. Just updated the firmware on our unit and we no longer get the message that the speed sensor wire has to be connected to use wireless Carplay.
 

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Discussion Starter #12
Small update:

If you have a multifunction steering wheel you should be able to adjust the setting for the MOST HUR-31 using the steering wheel controls. If you don't, you should be able to use the turn signal stalk. We don't have a multifunction steering wheel but could not use the turn signal stalk to reduce the gain. I talked to Tony over at NAV-TV and he sent me links to firmware updates with a couple of different gain settings. However, our module wouldn't connect via USB. Finally ended up sending the unit back to NAV-TV to be checked out and a controller chip was burned out so they replaced it. The replacement does connect via USB but I still can't adjust settings using the turn signal stalk. Luckily, the firmware that Tony flashed before sending it out seems to have a good gain setting for our needs.
 

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Discussion Starter #13
Couple more things:

I can’t seem to find the post now but I recall seeing someone else that installed the MOST HUR 31 put it in an accessible place because every once in a while it wouldn’t power up and had to be unplugged. We have had the same thing happen about 3 times so far. Our module isn’t accessible but pulling the PCM fuse seems to do the trick. That said, it’s still not an acceptable solution so I’ll have to get with NAV-TV or the shop that installed it.

Not directly related but on some songs with heavy bass there was a rattle in the driver side door. After removing the door panel and not really finding anything loose that seemed like it could rattle I was eventually able to pinpoint it as the directional pad used to adjust the mirrors.

Removed the switch module and dismantled — at least partially. I couldn’t fully separate the halves but got it far enough and removed 2 of the metal clips to release the silver trim around the pad. That allowed me to separate the black cap of the pad from the white stem/tube it was attached to. The rattle seemed to be between those 2 parts so I trimmed some felt tape to fit the underside of the cap and reassembled.

That took care of the rattle but it’s not a task I’d recommend. There a lot of little parts that can fall out and need to be put back when reassembling.
 

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I can’t seem to find the post now but I recall seeing someone else that installed the MOST HUR 31 put it in an accessible place because every once in a while it wouldn’t power up and had to be unplugged. We have had the same thing happen about 3 times so far. Our module isn’t accessible but pulling the PCM fuse seems to do the trick. That said, it’s still not an acceptable solution so I’ll have to get with NAV-TV or the shop that installed it.
I'd be very curious if there is a good solution to this.
 

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I constantly struggle with the idea of upgrading my stereo. It's puzzling why Porsche equipped such a beautiful car (2014 Box S) with such a horrible piece of crap like the Bose system. Cutting edge engineering meets outdated crappy integration of stereo electronics. I too have been searching all around for solutions. It's interesting that others have been able to take the base 3.1 and integrate both wireless Apple CarPlay with a back up camera as well. The cost for the unit is around $400 not including the rear camera which is around $60, plus labor of course. The Ali Express contact I had spoken with says they have a unit that works with the base 3.1 and are working now on a unit that will support Bose in Nav and non Nav formats. It's the only option I feel motivated by. Youtube does have a guy who shows the steps and seems to have had good luck with it. I applaud all who have shared their trials and tribulations with this process. The integration shown above is quite nice. Good job and thanks for sharing.

 

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I just found out mine has Bose CDR-31 no nav, so that makes it much more expensive because of the MOST interface.
Trying to add backup camera and Sirius XM to my 2013 Boxster
 
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