JakeW213

Hi all, as some of you have read from my other post, I have an issue with the aux. battery failure warning showing from time to time. Last time it showed the navigation went shot and does not show the car in the correct place. Now the aux. battery failure warning is gone again but the navigation is stil shot.

When I get into the car. Its positioned incorrectly(but different everytime and still somewhat close) when I drive it does not actually move but it like “stutter” moving a quarter of an inch and then resets to the beginning - like a half of second and then resets. (Maybe similar to an old record which is stuck in the same groove) Meaning it does not move anywhere from the initial wrong place under the whole trip.

Does anyone have an idea what could be wrong?

Also I have a general question regarding the navigation audio instructions. It seems like its set to default to be at sound level 27 - is there anyway I can change this other than altering it everytime? I like it at 15-20 but it will not save it!

joshg1001

I dont think this is related to the aux battery failure. I have had this in my car, and there is a GPS sensor in the side mirror that needs to be replaced.

whoover

You set the sound level with the volume control, but it has to be when it's speaking nav instructions. If you don't catch it, you'll be setting the radio/media volume level.

Your major problem can be a bad GPS module, or possibly bad wiring from the GPS antenna to COMAND.

JakeW213

Well if either of those it happened within the last 2 weeks, up until then it was working fine... I guess anything can break after a period and the car is old and used. And here I was, considering buying the extended 3 years of map updates...

Satnav via apple carplay works fine, so I wonder if its worth fixing? Any idea cost wise?

superswiss

Which would indicate that your GPS module in the car is fine. With Apple CarPlay, the phone uses the car's GPS signal.

JakeW213

Really? Well then I am back to the drawingboard... what can be wrong then? I mean, what you are saying crosses it out being the wires or the gps sensor... could it be the software then?

superswiss

Yes, based on my research on the Apple CarPlay spec and what others have said it uses the car's signal, because the phone is most likely tucked away and won't have good GPS reception on its own. However, what I'm not clear on is if the phone simply connects to the external GPS antenna, but it's still the phone's internal GPS circuit figuring out the actual location, or if it receives the processed location from the car. It's possible that it only receives the raw GPS signal, so what might be going on in your car is that the GPS circuit in your car is faulty and it fails to properly interpret the raw GPS signal. So it could still be that your COMAND head unit is malfunctioning, but the GPS antenna and wiring is fine.

whoover

No it doesn't. It uses the phone's GPS chip. Everything is the phone except the display.

Edit: Actually, I can't say for sure that MB hasn't implemented the local GPS provision for CarPlay. I use Android Auto, and it uses the phone's GPS, but I can't say for sure what CarPlay on COMAND does. I would suspect that, if your GPS isn't working and CarPlay nav is, it's an indication that it's using the phone's GPS hardware.

JakeW213

Can we agree on that if it only uses the Phone GPS - it would be handicapped by being put in the armrest and closed? I remember using my ipad mini(which has a gps connection) in Greece, from the backseat... I could only get a signal if I held it up to the side window, if it was laid on the rear seat bench in the middle of the car, the signal was gone - this makes me believe that the antenna needs a somewhat clear access to the satelites. So it make perfect sense if apple carplay would try to use an external antenna.

But your answers still leave me at my starting point -

Does anyone have an idea of what cost I am looking at if its:

Comand unit failure?
GPS sensor failure?
Wire failure?
Software failure?

I got a price for a software update(the newest) that will give me the option of running applecarplay and MB navigation at the same time plus updating to newest maps for roughly $450

but I don’t know if it will fix anything

superswiss

Yes, that's my point. GPS requires line of sight. Any obstruction even trees and tall buildings can block the signal. Signal reflections are also an issue, which is why phones often have troubles in dense cities with tall buildings. For example Google Maps jumps all over if I try to use it in downtown San Francisco. The car navigation systems work better in cities, because they also use the wheel and steering angle sensors in addition to GPS to get a better lock on the current position. As I said above, the phone may indeed use its internal GPS circuit to decode and process the GPS signal, but very likely it uses the external antenna to get a clear signal even if you put the phone in the arm rest or anywhere else in the car where the GPS signal may get blocked. I know MB doesn't offer wireless CarPlay yet, but with that it'll be even more important as the phone could be hidden in the trunk in someone's bag. If I use CarPlay, my phone is tucked away in the center console front compartment, so pretty sure it wouldn't have a very good GPS signal on its own. Sorry, can't help you on the cost front. Without a diagnosis it's just guesswork on what might be broken. You may at least take it to the dealer and see if they can diagnose the problem and tell you what needs to be replaced, then you can decide if it's worth it.

whoover

At least for Samsung phones, GPS sensitivity has improved markedly in the last five years. A couple of generations ago, I remember having to hold the phone on the dash to get a GPS signal. Today, I always get satellite lock wherever the phone is (not even using Android Auto, so it has nothing to do with the car's antenna). GPS works in my home and most buildings now. I can't speak to iPhones, of course, but I would imagine the latest ones are much better with "seeing" satellites when shielded that a few models ago. It's the same as with cell signals. My first MB phone integration had a cradle that connected the flip-phone to the car's antenna. Now, with BlueTooth we can't imagine the phone anywhere in the car not having a strong cell signal. (Actually, that was the second generation, that allowed you to use a flip-phone. My C36 had a dedicated car-phone.)

Unfortunately, your COMAND nav problem can be any of those, or more. I believe there's a signal amplifier in the circuit between antenna and COMAND, for instance. A dealer or good independent shop can figure out what's going on quickly, but without the right equipment you can only guess.

superswiss

Well, you get a position lock at least, but that's not necessarily from GPS. What has happened in recent years is that Google, Apple etc. have mapped Wi-Fi hotspots among other things and use it to augment the GPS signal to get a more accurate and also quicker lock on the current position. They also use cell tower triangulation. The further away you are from a metropolitan area with a bunch of Wi-Fi hotspots the more the phone has to rely on GPS alone and an unobstructed line of sight. You might remember that with the first GPS enabled phones it sometimes took forever to get a lock on your position. That's what happens if it only uses GPS. Today, phones pretty much get an immediate lock, but if it gets a GPS lock in addition, the accuracy increases. Apps like Google Maps and Apple Maps for example indicate this with a wider blue circle around your position, which gets smaller and smaller the more position information it receives. In addition to that the map apps also do some heuristics to determine what the most likely road is you are currently on, so having the system give you your current position doesn't necessarily mean that it has a GPS lock. If you use location history, you can see how sometimes the phone doesn't have a good lock on the current position while driving, especially out in the open. The GPS signal also drifts a lot in phones. There's a good article from a Google Maps developer on the subject. I post it if I can find it again. You'd be surprised how difficult it is to get a good and accurate position in a smartphone.

whoover

I have used the GPS on my latest phone on airplanes (yes, I know that's not airplane mode) and have locked over a dozen satellites. Clearly, it wasn't using known wifi routers from 35,000 feet. I also regularly use GPS status apps on the phone, so I am sure that the GPS is providing location info. BTW, Samsung phones have a status icon that tells you when the GPS service is active. It's easy for me to tell if COMAND is going to the phone for GPS info by watching for that icon on the phone when using Android Auto. I don't know of a way for the head unit to use the phone's GPS though the car's antenna. I've never seen anything in Android Auto or CarPlay API's for that and I also don't know of a USB pinout that includes providing GPS signal input.

whoover

I just ran another test that confirms Android Auto maps only uses the phone's GPS. I turned off location services on the phone and got this message:

I tried restarting Android Auto, even rebooting the phone and COMAND. Always the same: if the phone's GPS service is off, you can't navigate in Android Auto.

superswiss

No, sorry, but that is no proof. Turning off location (GPS) service on the phone turns off location altogether, meaning you are denying every app to obtain the phone's current location. It doesn't matter how the phone gets the current location. You really need to distinguish between he location service, which is an application API, the GPS circuit on the phone and the GPS antenna. The phone can still use its own GPS circuit, but rely on the car's GPS antenna, but ultimately if you turn off the location service, then no app can obtain the current location. I think we've taken this far enough w/o getting further into the engineer weeds and start dissecting the hardware or get some clear specs from the phone manufacturers and MB's implementation of CarPlay and Android Auto. Given that certain features of CarPlay and AA are optional and don't have to necessarily be implemented by the car manufacturers, more information is required to clearly determine which GPS antenna the phone uses when connected.

whoover

Fair enough, but I'm still curious about your thesis that "the phone can still use its own GPS circuit, but rely on the car's GPS antenna." Lacking an antenna line in the USB spec, how would that happen? I understand everything you're saying except this, so I suspect I might be missing something. Are you thinking that maybe some sort of inductive pickup could be effective, or is there a defined mechanism for an external GPS antenna via a USB connection?

fleuger99

I disagree with your statement. My brother has a Golf and it didn't come with Nav but he uses apple carplay and his phone instead to navigate when needed. Apple Car play and ANdroid auto do not use the vehicle for nav.

whoover

Obviously, if the car doesn't have nav, Google maps or Waze can't use the car's nav. The discussion is about when, and under what circumstances, the location service that the mapping app uses will use the car's GPS. Both CarPlay and Android Auto have provisions for the nav app to get the location info from the head unit if it has GPS. If it doesn't, no, it can't use it.

fleuger99

Try reading what I said, before making assumptions. I never said it uses the car's Nav, how could it if it doesn't have one, obviously! What I said was Android auto or Apple Car Play don't use the vehicle at all for navigation, never said it uses a nav that doesn't exist.

fleuger99

I actually just read that Android Auto will use which ever has the stronger signal, the phone or the auto's signal if the car has one. If not, it will only use the phone's signal.

whoover

OK, I've read it twice. I have no idea what you mean. What would "using the vehicle" for navigation mean if it's not its built-in nav (which the CarPlay and Android Auto specs allow for). What am I missing?

The_Judge

I suspect that what he's referring to is the fact that your phone uses its own GPS function for navigation, just as it does when you're walking around with it.

whoover

But the entire thread has gone into great detail about when it uses its own GPS and when it uses the head unit's. If you ignore the rest of the thread, that comment could make sense. But it surely doesn't add much to the discussion.

SunnyC257

Have a read through this thread: http://www.mbworld.org/forums/e-clas...incorrect.html

Music_Lover

Long thread...
Did we agree on how Apple CarPlay work?

Is it using the car’s GPS signal or the phone's GPS chip? (Phone chip = navigation is managed by the phone and the display signal is sent to the MB 12” screen)