Hey gang,

This is regarding my "991S Boxster" ('13 981 Boxster + '14 991S engine, etc). Although I've been busy doing updates to my PCM 3.1 (Cloned internal 40GB IDE hard drive and replaced with mSATA...made a working backup...plus installed a Joyeauto unit for CarPlay and a rear-view camera), I noticed a new wrinkle today.

Basically, I was driving on Boston's "Big Dig" on I-93, which goes underneath the city. NAV was working great. Understandably, you lose GPS reception for a few minutes when you go through the tunnel. But for 10+ minutes afterwards on my way home (and continuing until now), the PCM never got a new GPS satellite fix. In the garage, it still says that the number of satellites are zero...and my location shows up on the maps in the middle of Boston Harbor! LOL.

Plus, I've always gotten a GPS inside my garage up until now. So for whatever reason, it's not getting a GPS satellite fix.

Anyhow, I'm wondering if this has something to do with the GPS antenna. If so, the question is -- where is it? Is there an external connection to the PCM that maybe I accidentally unplugged?

Now that I have my maps back (see "Loading maps" error thread), the NAV system has worked great again until now. Again, this has never happened before.

Thanks, everyone!

 

That sure sounds like an antenna issue. My 981 Cayman's external PCM antenna is a little lump on the roof of my car. I assume the Boxster has the same somewhere else on the body and there has to be some sort of connection the the unit itself, however unfortunately I dont know enough to tell you were that connection is. Its the last thing you were working on, and all of this started happening afterwards, so it sure sounds like that's the source of your issue. The bad news is you will need to tear back into it again, but the good news is likely something simple that just isnt connected properly and an easy fix

 

Thanks, @ICNU ! (Nice color, BTW. Did you pop in the GTS tail lights or keep them red? I'm on the fence here...)

I agree per the reasoning here. The last two things I was working on was (1) hooking up a PIWIS to clear the oil change reminder...which was likely unrelated and (2) I was backing up the hard drive for the PCM. So it's probably the latter.

Meanwhile, I was having a terrible time getting the PCM back into the dash the other day -- which included compression of the wires. So the first thing I've done is to check the wires on the back of the PCM. From a prior thread, I checked the blue connector, in which someone else had a similar issue as theirs was loose. The connection at the PCM both looked and felt okay; I disconnected and reconnected it to be on the safe side, so that's probably fine. Looks like a tiny pigtail connector.

Another interesting thing is that physically moving the PCM -- moves the compass reading AND the direction of the car arrow symbol on the NAV. I guess that has nothing to do with acquiring satellite signals.

Otherwise, I don't know where the antenna goes on the Boxster -- as it's pretty clear on the Cayman. Meanwhile, I didn't move any antenna wires from what I remember.

I have also tried resetting the PCM a few times (hard reset, vehicle handover, etc.). Again, the NAV works and the maps are there -- which was a previous battle.

What is really bothering me is that it was working absolutely fine and the NAV has been fine for weeks since I got the maps restored. But the one time that I actually lose my GPS signal -- something doesn't seem right where it simply won't reacquire the GPS signals again. Again, I've never had this issue before.

Again, hopefully it is indeed simple but I can't seem to figure it out yet...

 

That is a head scratcher. I do now recall a post either here or on Planet-9 a couple years ago where someone with a 981 was claiming that their previously working Navi suddenly started showing their position miles away from where they were. This was a random event and if I recall no amount of waiting or driving would let thinks sync back up. I dont recall if there was ever a solution, but I'll see if I can find the thread for you. Did you happen to go into the location info tab on the unit and see how many satellites the unit is connected to if any? That should rule out an antenna disconnection if you are indeed connecting to sats

Yes, I like the loud colors and this is my second yellow Porsche. My previous was Speed Yellow on my Boxster I had many years ago vs the brighter Racing Yellow on my 981. I do plan on swapping out the tail lights for the GTS versions as I think they help to break things up a bit back there on certain brightly colored cars.

My 981 is a 2014 and was one of the first to arrive after the new 981 Cayman version was released. I went in for an oil change on my 987 and left with the 981, so most expensive oil change ever!It was built in May 2013, so 8 years old this month and Im debating on attempting a pro-active PCM drive clone/change.

Cloning a drive would be a first for me, but it looks fairly straightforward from the last few years of reading of others doing it, but Im also afraid of causing an issue when there isnt one now, and luckily my PCM has been working just fine so the old "if it aint broke dont fix it" seems to apply a bit here.

I have a lift and do all my own service and not afraid at all to tear into something mechanically as I've restored a few classic hotrods and rebuilt the engine and drivetrain all on my own without issue, but the electronics on these modern cars scare me. Especially since the PCM on the 981 is not just a radio/Navi on its own island as in many cars, but is part of the overall electrical system and can cause gremlins elsewhere downstream


EDIT: Found a couple of old discussions with what seems like the same issue you are having, and there is a GPS antenna it seems, at least on the 987 being discussed in this old thread: https://www.planet-9.com/threads/wro...-in-gps.20279/

Here is the one from the 981 I recalled, but it wasnt good news other than to replace the unit. In my searches I see that is seems to be a common PCM issue going back years on both the Boxster/Cayman and 911 models.

Good luck on the quest here and it will be interesting to see what it turns out to be

 

Thanks again across the board, @ICNU. As my "991S Boxster" is Racing Yellow as well -- good to hear that I'm not the only one that's thinking about the GTS tail lights per the yellow. I'm beginning to wonder if the big swaths of red is a bit out-of-place with the rest of the car being black/yellow/silver. As for the yellow itself, I think I've hit that point in my life where (1) I'm finally starting to stop worrying about other people judging me (in this case, my driving a very loud color P-car) and (2) just have fun with it. That's why it's a sports car! Kinda the "go big or go home" thing.

Also appreciate those links. I had seen the latter, and was a bit disheartened. Yes, ZERO satellites. The fact that it was working absolutely fine but couldn't reacquire them -- that is a bit of a head scratcher here. Makes me wonder if either it's (1) a software bug or (2) the satellite signal was weak to begin with (maybe I recently damaged the antenna wire by smushing the PCM back in?) and it can't acquire any now? The only state change when it stopped working was a complete dropout of all satellites when I went underground. The fact that there's ZERO satellites makes me think it's an all-or-nothing situation somewhere -- and I doubt I damaged something inside the PCM internally (at least I hope).

Only other recent thing was I had to rewire my radar detector's power tap -- which is near the rear view mirror. I read something about the antenna being near there? Maybe something is loose in that area? Haven't been able to figure that out yet.

Very cool per the 2014. Looks like we've got "early 981s" in common as mine is a 2013. LOL per the oil change story! Moved up as well from my 987.1 to this and I'm totally digging the style changing.

Tough call per the drive cloning thing. Again, I'm wondering if that has something to do with my issue here...I was even reluctant to go back in and make a backup copy of the drive as I finally got everything working again. Definitely the "ain't broke" situation. Having done so many electronic upgrades and stuff in the past few months -- this is a huge contrast from having sold my '68 VW bug convertible -- and I hope I didn't invite more electronic gremlins. Meanwhile, when everything is working correctly -- this car is turning out to be very awesome.

 

Foodbiker,
IIRC the gps antenna is behind the rear view mirror so I would look there for a possible loose connection or damage when you worked on you radar detector. The wart on the Cayman is the XM radio antenna and not sure where it is on the Boxster. The blue connector on the PCM is for the GPS antenna.
Jim

PCM connections

 

There are anomalies in GPS signals. Sometimes on purpose, if testing. I receive notice to airmen warning on these occasionally. Twice, in our Mercedes, map has shown that we are off the map, somewhere in the Atlantic!

 

Jim's definitely on to something here. If you already checked the connection at the rear of the PCM and it looks okay, try checking the other end. The antenna itself is in the assembly behind the rearview mirror. Since you were working up there on the radar detector wiring, maybe the antenna end of the cable came loose.

 

Thanks, guys. Really appreciate it. After spending weeks of slowly ironing things out and finally getting everything in good shape, this was such a huge downer this afternoon to have this fail -- and disheartening to read that others have had issues where the PCM indeed required replacement.

Meanwhile, the fact that it failed in the middle of the tunnel -- makes me think that something hardware-wise certainly didn't come loose at that exact time where it simply couldn't reacquire a signal upon exiting the tunnel.

I did check the BLUE connection behind the PCM and that seemed pretty solid.

Looking in the rearview mirror area, I'm having a tough time figuring out what is what. The only thing I moved in that area was the mirror itself (which I knocked off its post with my head) and the yellow connector which where the tap was from - but that was under the reading lights panel.

Per the latter, I didn't see anything in there (2013 Boxster) that appeared unusual. I'll try and check the connections again. The blue connector on the driver's side appeared snug and I didn't touch anything on that side when re-tapping the radar detector.

Meanwhile, I’ll check the mirror (not the reading light) area tomorrow.

Any other thoughts, please keep them coming. Thanks, everyone!

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MORNING COFFEE UPDATE: Although I haven't done any more exploratory work on the car yet today, I often find that walking away from a problem -- let alone literally "sleeping on it" -- sometimes offers me a genuinely fresh look at the situation. Sitting here with my coffee, before I do anything, I can't help but reason that ideally, the PCM itself should be fine. Why?

Well, it was working absolutely fine until it encountered a specific situation where it lost all satellite reception...the huge tunnel under Boston... and it just can't quickly reacquire signals upon exit. The odds of that all electronically failing inside the PCM at that very moment seem slim-to-none. It did encounter that situation earlier that morning when I went through the tunnel, but there were no issues per quickly reacquiring a signal..

So maybe (For who-knows-how-long? A few weeks now after bonking my head on the mirror and knocking it off?), the NAV may have been "getting by" on picking up only a few GPS signals -- maybe just a bare minimum of satellites -- say 3-4? -- instead of something like 8-10. That would make sense if the antenna connection was indeed compromised. Although we're talking satellites here, the analogy might be a good-old FM radio in area with good reception...where you don't need to extend your antenna.

So by this reasoning, if I did nothing, I'd think that with a compromised antenna situation, I would think that the NAV should eventually be in a situation where it picks up only the strongest signals of satellites like before. Meanwhile, it would probably just show 3-4 satellites or the like -- which again -- would likely indicate an antenna issue. I would think that should have quickly picked up at least a few satellites in the 7 minute drive after the tunnel and in my garage, but that hasn't happened yet.

Anyone want to chime in, feel free and I'm all ears. Meanwhile, I hope to look at the mirror area today.

 

LATE AFTERNOON UPDATE: Internet (Xfinity/Comcast) has been down all afternoon and just came back on.

Still no luck.
Zero satellites.

Here’s what I did per today's troubleshooting:

1) Back of PCM — Checked female connector on PCM itself. Looks fine. Center pin is both intact and straight. No apparent damage.

2) Antenna area near windshield — I removed both the antenna wire (the other BLUE female connector) and the antenna board itself. Antenna board looks fine. Center pin intact and straight. No apparent damage.

3) Tested the complete antenna wire run (BLUE connector to BLUE connector, black wire) running from the PCM all the way to the antenna area near windshield. I ran continuity tests from both center pins at each end, plus the external wire connectors. The wire is completely intact, with no shorted or broken connections. So physically, everything seems to check out.

4) Reconnected BLUE connectors at both ends for tight connections.

Still nothing.

Tomorrow I’ll be going for a good 20+ minute drive, and hopefully it’ll magically and eventually pick-up multiple GPS satellite signals outside of my garage.

No, I’ve never looked to see if the PCM picks up satellite signals in my garage. Yes, there is indeed a lot of concrete. Meanwhile, I do remember that the location is always correct when the car sits in the garage...but I wonder if that may be the last known location before I pull into the garage.

Again, the only other two recent changes to the car were (1) swapping out the PCM drive with a cloned backup and (2) running the PIWIS system. That’s all. I’ve got my maps and pretty much everything else seems to be working fine.


I can't think of more, but I think my upcoming game plan should likely be:

1) Drive the car for a while tomorrow. See if it picks up anything at all.
2) If that fails, try a very cheap generic GPS Navigation Antenna with the standard blue Fakra C connector -- and plug that into the PCM. If that doesn't work, that seems to indicate that the issue may be internal to the PCM.
3) If that fails, try swapping back the mSATA drive that I had cloned. (This seems super-unlikely, given the issues don't seem to match up. If I had no maps loading at all, that might be the PCM hard drive issue).

Again, any thoughts/suggestions, I’m worried that I’m running out of options here.

 

PHEW! Potential promising headway (aka, mystery partially solved... aka, problem hopefully solved as good enough as it can be solved...).

1) I went for a ~45 min drive yesterday and thankfully the satellite signals started to return in about 5 minutes! So very relieved here...although this may not be entirely fixed and more on that in a minute. From my research, 3-5 minutes if you're starting from zero satellite signals acquired is realistic. What's weird is that it didn't reacquire signals after exiting the tunnel, which was clearly 5+ minutes of driving -- which didn't seem normal at all.

2) I'm guessing that my concrete garage was blocking GPS signals somewhat...or maybe it's because the car was parked and not moving? Meanwhile, I left the car overnight and without starting the car or moving it, with the garage door closed, it's showing ZERO satellites again. Come to think of it, it makes sense that it would have to acquire new satellite signals after every boot -- like how older hand-held GPS units used to work.

3) During yesterday's drive, I watched the "INFO" page to continually monitor the number of satellites. I also did that on the 20+ drive home. It appears that the range of the number of satellite signals acquired varied anywhere from 6-11. The average seemed to be about 6 to 7.

4) Meanwhile, twice during the first drive and once during the second drive, there were ~5 min dropouts where the number of satellites dropped back down to ZERO! You can imagine that my heart dropped each time. What confused me is that the location continued to correctly update on my maps. So the key point is this -- the NAV appears smart enough to use dead-reckoning per both the compass and the internal maps to compensate from the last known location. That's why each time I pull out of my garage, although there are no satellites yet, the maps still seem to work. So this makes me think that the problem of brief drop-outs may have been always there...and I'm only noticing it now given last week's prolonged GPS dropout in the tunnel... with the map location getting confused.

5) Again, I think this is may be an issue that just happened to coincide with a bunch of other work on the car. Now, I'm really beginning to doubt that I bumped anything loose or the like or damaged the antenna wire, and the PCM itself has likely been just fine all along. But this past weekend, I would have bet big bucks that I had personally caused the issue given my work on both the PCM and in the mirror area -- the odds of this surfacing out of nowhere seemed too great to ignore.

6) So why the occasional dropouts? I'm thinking three possibilities. The drop of ALL satellite signals and not a reduced number might indicate (1) a loose connection or a break in the antenna wire...which I think I've ruled out, (2) a failing antenna card, or (3) RF interference. Given that the dropouts appear to be brief (<5 minutes) and my having measured the antenna wire continuity, now I really doubt it's the former two.

Per RF interference, I'm using my iPhone with a JoyeAuto unit, and the iPhone is connected to a USB cable that is in the passenger footwell. Given the ton of data being transmitted (Pandora, Waze), that the JoyeAuto uses WiFi (and I think also Bluetooth?), maybe there's some RF interference going on? Another possibility may be that I just happened to drive in areas that temporarily knocked out all signals -- as I was driving in both a city and om densely populated suburbs. In the last instance, I did unplug the iPhone after a few minutes of lost GPS reception, and the GPS signals did come back -- but I don't know if that was a coincidence or not. (I had to be careful as I was driving on I-93.)

7) Again, I keep wondering if there's absolutely any chance of a loose connection? I doubt it, as the dropout intervals seemed to be about the same (~5 min) and were transparent to me unless I was specifically watching the number of satellite signals acquired, given that the NAV apparently continues to calculate one's location. Plus, I had also checked the continuity of the antenna cable, which seemed just fine.

8) So, what's my plan?

* FINALLY put everything back together today; hopefully I will NOT have to go back into my PCM anytime soon.

* I'm considering buying a replacement used antenna (not the wire, but the small card at the end of the antenna wire that's affixed to the windshield area) and see if it makes any difference. I'm pretty confident that the PCM is just fine given that it reacquired signals in the first place -- and the antenna wire's continuity is fine with no breaks or shorts. The antenna car is the only thing I can imagine as a faulty part here -- either as failing or just generally weak.

* I was considering playing around with a <$10 cheap aftermarket antenna with the same style connector to see if that makes a difference. Meanwhile, I really want the stock look and OEM internal parts if at all possible.

Anyhow, I do have this nagging feeling that occasionally losing all satellite signals may be "just normal" and nothing is actually wrong in the car itself. Given that many people now use Waze/Google Maps anyway, I may just live with it -- given that the NAV covers up the temporary signal loss with the dead reckoning/compass thing. I like to use the real-time map in my instrument cluster, while using actual navigation using Waze...so I might just let it all ride for now. If I do completely lose the signals all over again (like going through a tunnel), my guess is to just be patient and let it reacquire them. I just hope I don't freak out the next time it happens!

Finally, if anyone else with a NAV system (especially with JoyeAuto and an iPhone connected via USB...maybe some Bluetooth) is up for driving around for a while with the INFO information per the number of satellites -- and see if they ever have entire dropouts and/or the average number of satellites you acquire -- I'd love to hear what you find. Now I'm just wondering if this entire situation is "a feature, not a bug" and is just how it works.

Thanks, everyone!

 

I have never paid any attention to the number of sats on mine before, but will try and remember to take a look on my next outing with the car and report back. The first time a GPS antenna acquires sats of a specific location is when things will take the longest. After that, there are tables stored so the connection is typically faster from then on. You cannot expect to see any sats when indoors in the garage depending on the surroundings and materials. The same reason that sat radio drops out when you pull into a parking garage, so all your testing needs to be done outside with a view of the sky

 

Thanks, @ICNU ! That's great info. I'm just relieved that things seem to be working as normal...but it's just the weird satellite "dropout" where it loses everything for about 5 minutes that's just so gosh-darned puzzling...but the fact that those drop-outs are masked by the "dead reckoning/compass" computations exist makes me think this may be more common than I'd expect.

Thanks for doing the INFO satellite test and letting me know what you see!

 

I have a 2013 BS but don't use NAV since the maps are out of date. For my own curiosity I will check my INFO for satellites. I have GPS Test on my phone. It shows 24 satellites in view and 16 used. I had an old S3 phone which were notorious for the GPS antennae connection failing. I suspect you have a failing GPS antennae. As suggested you might get a generic antennae to test first.

 

Dynamite, @Kitc2246! Thanks for checking as well, especially given that you too have a 2013 Boxster with NAV. Really appreciate it. Given that used antenna cards don't seem that pricey on eBay, I may just go that route anyhow and see if it makes a difference. To be honest, swapping that out would be a LOT easier than dealing with the PCM removal headache to install an aftermarket antenna. But thankfully all this wouldn't be bank breaking like a PCM repair.


***********

Also decided to just go ahead and order an identical replacement antenna (same part) from a 982 (718) Cayman. Part number was identical (manufactured in Poland and not Tunisia) and wasn't too expensive as I found it used. Curious to see if I notice any difference or not.

Meanwhile, looking forward to hearing from your experiences per # of satellites!