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I have an Accord Hybrid Touring 2017, and here's the curious problem I was having:

- When using CarPlay, Apple Maps and any other GPS app show far less accuracy in location, sometimes up to 400 meters away from where I actually am! At that point, the Map application is basically having me turn on streets that are far away from me, and basically goes nuts. It's distracting and potentially dangerous.
- If I un-plug the phone from the CarPlay port, the GPS accuracy is immediately restored, and Apple Maps, Google Maps, etc. work as expected
- Plug the phone into any other USB port (not the CarPlay one), and GPS still works as expected
- Plug back into the CarPlay port, and GPS resolution issues return immediately.

For the record, I have an iPhone 7Plus, running the latest iOS.

Then I found this great video on YouTube, where one user demonstrated the use of an app called GPSdiagnostic to positively show that GPS resolution and reception from satellites is dramatically impacted as soon as CarPlay is active (that is, you're plugged in to the CarPlay port). Search YouTube for "My Waze SPEED anomaly...solved!" (I can't post links yet, since this is my first post). In my case, when I plug the phone into the CarPlay port, Satellites 4-12 disappear entirely, and others are reduced to 50% or less quality, and accuracy (when stationary), is erratic at 200-400m!

I just called Honda to let them know about this issue, and I'm told I'm the first one to report it. Either it's a part issue, or something that's impacting others as well. Please do call in if you have the same problem.
 

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I have an Accord Hybrid Touring 2017, and here's the curious problem I was having:

- When using CarPlay, Apple Maps and any other GPS app show far less accuracy in location, sometimes up to 400 meters away from where I actually am! At that point, the Map application is basically having me turn on streets that are far away from me, and basically goes nuts. It's distracting and potentially dangerous.
- If I un-plug the phone from the CarPlay port, the GPS accuracy is immediately restored, and Apple Maps, Google Maps, etc. work as expected
- Plug the phone into any other USB port (not the CarPlay one), and GPS still works as expected
- Plug back into the CarPlay port, and GPS resolution issues return immediately.

For the record, I have an iPhone 7Plus, running the latest iOS.

Then I found this great video on YouTube, where one user demonstrated the use of an app called GPSdiagnostic to positively show that GPS resolution and reception from satellites is dramatically impacted as soon as CarPlay is active (that is, you're plugged in to the CarPlay port). Search YouTube for "My Waze SPEED anomaly...solved!" (I can't post links yet, since this is my first post). In my case, when I plug the phone into the CarPlay port, Satellites 4-12 disappear entirely, and others are reduced to 50% or less quality, and accuracy (when stationary), is erratic at 200-400m!

I just called Honda to let them know about this issue, and I'm told I'm the first one to report it. Either it's a part issue, or something that's impacting others as well. Please do call in if you have the same problem.
I have the same issue and just found your thread. I posted about it recently - http://www.driveaccord.net/forums/1...ng-incorrect-location-when-using-carplay.html

Assume you have no resolution?
 

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Hmmm... would this not be an Apple issue vs. Honda? Honda is not using the built in GPS chip during CarPlay, no? Isn't phone GPS chip used?

(actually I might be wrong about that actually do not know)

EDIT: Not conclusive: Carplay - Apple Community

Also - I have Pioneer 4200NEX units in two of 3 cars at home. They can both use CarPlay and do, with our phones. As far as I know, there is no GPS chip in those units, at least they are not "navigation" units (but I guess it is possible that they have a GPS chip on board).

I remember a thread somewhere around here that allowed you to see GPS satellites that your in-car GPS chip sees; even if the unit does not have navigation, the GPS chip is still there.

Okay, I now bought the app and did a few tests too and I believe @shuffaccord is onto something.

I took two screen shots of the app; on the one from when the phone is plugged into the unit, the phone GPS app shows significantly increased GPS strength and improved accuracy. Both of those screenshots were taken when stationary (accuracy would improve in both cases if the car was moving, I believe).

I will do a similar test with an aftermarket Pioneer unit I have in two other cars, as I am interested. But my conclusion is that iPhone does use the car GPS when plugged in and therefore - if GPS signal goes down, there might be issues with in-car built GPS.

To help diagnose this more, @shuffaccord, see this thread; the dealer should be able to do this test and see if satellites disappear when phone is plugged in?

2017 EX GPS chip?

Plugged in (iPhone X with my 2017 Accord EX):


Unplugged:
 

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Thanks for helping troubleshoot this, but aren't your screenshots saying that GPS reception should be improved using carplay as opposed to worse like the OP and I are seeing?

Is it somehow known that the car's GPS would be more unreliable than the iPhone's GPS? And if so, why would Honda do this? Why wouldn't they just let the iPhone use it's own GPS, which in my experience is very accurate?
 

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Well, I am back to square one, really. I just went and re-did the test and got 100% GPS whether the phone is plugged in or not. So... still inconclusive.

I think OP's point is that there might be something going on that makes the head unit drop GPS signal as soon as the phone is plugged in. I do not think this is an universally true thing; my phone definitely do not support that. But I am not sure (still) if the signal drop that OP sees is because car GPS signal or phone GPS signal. The only way to know for sure what happens to car GPS signal is to run the car head unit in diagnostics mode as per the linker thread and then see what the head unit itself says. If there is a drop in GPS signal when the phone is plugged in vs. not.

There might be an issue on OP's car, or a specific series of cars or something.

One interesting thing is that as I was poking around the app, if you press the help bubble for "Datum" it says that if this is set incorrectly, the GPS signal will show wrong by few hundred feet. What if this setting is messed up somewhere?
 

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Well, I am back to square one, really. I just went and re-did the test and got 100% GPS whether the phone is plugged in or not. So... still inconclusive.

I think OP's point is that there might be something going on that makes the head unit drop GPS signal as soon as the phone is plugged in. I do not think this is an universally true thing; my phone definitely do not support that. But I am not sure (still) if the signal drop that OP sees is because car GPS signal or phone GPS signal. The only way to know for sure what happens to car GPS signal is to run the car head unit in diagnostics mode as per the linker thread and then see what the head unit itself says. If there is a drop in GPS signal when the phone is plugged in vs. not.

There might be an issue on OP's car, or a specific series of cars or something.

One interesting thing is that as I was poking around the app, if you press the help bubble for "Datum" it says that if this is set incorrectly, the GPS signal will show wrong by few hundred feet. What if this setting is messed up somewhere?
How would you even know if that datum setting is messed up?

I have not been able to get into diagnostics mode on my 2017*Accord*EX-*L*V6 with sensing. I tried the power, menu and display buttons as I've seen and it doesn't do anything.
 

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I just heard back from the developer of the GPSdiagnostic app.

There is essentially no API for him to show in the app which GPS chip is being displayed in the app at this time. However, if there is a significant difference between when plugged in and unplugged, I would think that is an indication of one vs. the other. So - if satellites 4> disappear when plugged in, it sounds like that could indicate an issue on Honda side?

I just went to my car and got into developer menu first try; I found a video on YouTube that explains how to do it (but he says that it works for EX only, not sure what that means). There are a few videos there, see if there is a difference between the procedure?

For me, there was no difference in GPS satellites on the HU whether my iPhone phone was plugged in or not:

 
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