CarPlay Does CarPlay use HU GPS or phone GPS?

[bigboy29]

I have looked and looked and did not find a conclusive answer - perhaps this is more known now:

When using CarPlay, will the phone use the GPS chip in the car HU to improve accuracy, or will it use phone GPS only? I know map data obviously comes from the phone itself.

For example - I know that my 2017 Honda Accord EX has a built-in GPS chip (even though the unit does not have navigation). I also use a Pioneer NEX unit in other cars but I do not know if those have GPS in them or not.

 

[Sir Ruben]

I bought a Pioneer CarPlay HU and I can confirm that it came with its own GPS module with a long lead. One end plugs into the back of the HU and the other end sticks to the underneath of my dashboard (behind the glovebox). Presumably it always uses that but its hard to say.

 

[bigboy29]

My limited testing seems to indicate that CarPlay will use the GPS chip on the HU. At least that seems to be the case with my 2017 Honda Accord EX (the unit does not have navigation but does have a GPS chip).

I took two screen shots of the GPS testing app on the phone; 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 (note that my Pioneer units - 4200NEX - did NOT come with a sensor that is plugged in but there could still be one that is built in for CarPlay purposes only).

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

Unplugged:

 

[bigboy29]

Well, back to square one; still not sure what happens. I tried the same test now again and got 100% GPS signal in a car whether the phone is plugged in or not. So... (shrug!)