Jason Stewart

I bought the Road Top Wireless CarPlay unit ( ) and have a question about installing it in my '13 GL550.

The instructions say that in order to get audio from the unit you have to run a cable to the AMI port in the center armrest console. In my case, I'm already using the AMI port for AUX video input, so I'm trying to figure out a way get the audio from the Road Top unit into my audio system some other way.

A couple of questions:

1. Bluetooth. Has anyone just used the Phone -> Car bluetooth connection to get audio into the system (when using CarPlay)?
2. Direct Wiring. Is there a way to directly wire the AUX Output from the Road Top module into the GL550's head unit (without having to run the cable to the AMI port in the center console)?

EDIT 1: This post seems to indicate that all that's needed is to turn on "Audio AUX" in the engineering menu. I'll test it out and see if it overrides what I already have plugged into the AMI port.
EDIT 2: I installed the Road Top CarPlay box and found that if you enable "Audio AUX" in the engineering menu in vehicles that AMI port, the AMI port is disabled and the receiver will use the Audio AUX built into the head unit. You can NOT have the Audio AUX built into the head unit AND the AMI port enabled at the same time (my guess is that there is a single Auxiliary Audio Input in the head unit that accepts either audio from the AMI port OR the built-in Audio Aux port, so using both at the same time isn't possible).
EDIT 3: Also, found that you can connect the the MB system via Bluetooth AND use CarPlay at the same time. This is convenient for retaining the use of the head unit's prev/next track buttons (when connected to bluetooth and CarPlay) but the down side is that when connected to bluetooth with that source active on the MB head unit you will NOT hear navigation directions; if you have Audio Aux as the MB head unit's source and you're also connected via Bluetooth to the MB system, you will not hear any music but you will hear voice guidance for navigation directions. The only way to hear both music and voice guidance directions on a single source (i.e. Audio Aux) is to either disconnect CarPlay and activate Bluetooth as the MB system's audio source, or disconnect the phone from the MB system's bluetooth and set MB system's audio source as "Aux" (but you lose the ability to control music, like prev/next, with MB head unit buttons).

cadetdrivr

Correct. I have the RoadTop unit installed and have no connections to the AMI port. You will still want to connect your phone via bluetooth to the truck for clear phone calls using the MB mics and noise canceling. Unless there is a change in the newer RoadTop units, you cannot connect the RoadTop unit via bluetooth to your Comand unit for CarPlay audio.

Caveat #1: I'm in the USA and have HK audio. Some forum members have reported that the Engineering Mode hack does not work for them for reasons we don't understand. There are apparently geographic differences with the logic, audio systems, and/or other.

Caveat #2: The behavior of the Comand unit can change if there is something plugged into the AMI port. You may, or may not, have to unplug the video connection to the AMI port for proper logic. Note that the RoadTop unit has a HDMI input that you can use instead of the AMI port for video, but that would only provide video on the OEM Command screen.

cadetdrivr

FYI, you are posting in a subform where none of the vehicles have wired factory installed CarPlay.

Jason Stewart

Thanks @cadetdrivr ! What about connecting the phone to the MB booth system and then setting the Audio source to "Bluetooth Audio" (instead of Aux)? In that case, when CarPlay is active on the screen, wouldn't you get Audio coming through the MB system from the phone?

@cadetdrivr in your case, did you have to set Aux Audio to "on/enabled" in the engineering menu to get your CarPlay audio to play through your MB's HK system? Or did audio work without the Engineering Mode hack to set Aux Audio to "on/enabled"?

@cadetdrivr That's a good point. If I end up having to run the AUX audio cable from the Roadmap unit to the AMI port, I thought I could use a to toggle between AMI sources. I would prefer NOT to have to run the AUX cable through the center console armrest, so we'll see if the MB system can function properly with both an Aux Audio source AND something plugged into the AMI port.

@Mandel Nope, X166's don't have CarPlay built-in.

cadetdrivr

@Jason Stewart
Unfortunately, no. CarPlay will only output audio via its own protocol(s).

I had to do the engineering hack on both my cars (GL350 and E350) and the E350 was the first install. Both are 2014 models with NTG4.7 and HK. I installed an older generation Joyeauto unit on the E350 which lead to me successfully trying the hack with the RoadTop unit several months later on the GL.

cadetdrivr

@Jason Stewart One more thing. On both of my RoadTop and Joyeauto kits the main wiring harness for the kit has an otherwise unused analog input cable & plug in addition to the longer analog cable that is supposed to route to the AMI. You gotta plug the analog cables together to complete the circuit.

I've seen a report online that claimed their unit did not have that input cable, but I don't know the credibility of the report. If your unit does not have the input cable, then you may have to dig into the wiring diagram for the unit and do some splicing.

Jason Stewart

I installed the Road Top unit and learned a few things I thought I'd share related to my OG questions:

I found that if you enable "Audio AUX" in the engineering menu in vehicles that AMI port, the AMI port is disabled and the receiver will use the Audio AUX built into the head unit. You can NOT have the Audio AUX built into the head unit AND the AMI port enabled at the same time (my guess is that there is a single Auxiliary Audio Input in the head unit that accepts either audio from the AMI port OR the built-in Audio Aux port, so using both at the same time isn't possible).

Also, found that you can connect the the MB system via Bluetooth AND use CarPlay at the same time. This is convenient for retaining the use of the head unit's prev/next track buttons (when connected to bluetooth and CarPlay) but the down side is that when connected to bluetooth with that source active on the MB head unit you will NOT hear navigation directions; if you have Audio Aux as the MB head unit's source and you're also connected via Bluetooth to the MB system, you will not hear any music but you will hear voice guidance for navigation directions. The only way to hear both music and voice guidance directions on a single source (i.e. Audio Aux) is to either disconnect CarPlay and activate Bluetooth as the MB system's audio source, or disconnect the phone from the MB system's bluetooth and set MB system's audio source as "Aux" (but you lose the ability to control music, like prev/next, with MB head unit buttons).

NCWolverine

If you go through the Engineering menu to enable Audio Aux and disable the AMI Port, can this operation be reversed?

Have my Road Top setup sorted but hate the cable running to the glovebox. But should the Audio Aux change not work, want the peace of kind of moving back.

Thanks

cadetdrivr

Yes. It’s a toggle setting.

As a tip, I’d suggest using your phone to take before/after photos of the menus to ensure you document the changes if you desire to return the settings later.

Packrat555

2013 HK system here, I had to wire to console and plug into AMI using cable roadtop provided. It is not as hard as it seems. from the radio side use coat hanger wire and go down to floor board do same from console you can easily tuck cable under trim from there. you can tuck the ami cable connection behind the panel in the clover box. Find a panel mount usb extension and also wire it to where ami cable was I simply used hot glue to secure it from behind the panel. Now you have a usb input and a way to flash updates.

You also need to deactivate the navigation audio or when you press steering wheel button to talk to carplay you will also get response from mb navigation. Instructions are posted somewhere on this board

there are a few quirks about the roadtop box but I could not live without carplay now.

NCWolverine

After three evenings I was able to get the RoadTop setup installed and working in my wife’s 2015 GLK250.

I probably lost three hours to just getting the cables hidden and the head unit tucked away, and another 2 to 3 hours on the Audio working without using the AMI cable (thank you engineering menu).

Best part is the wife loves it.

Many, many thanks to all who shared their tips and advice. Y’all were a godsend.

ccrobin

I just received my Road Top kit yesterday and it only took about 45 minutes to install. Very happy with it so far. The AMI connector that came with the kit was junk (lots of distortion and feedback) but I also have the factory AMI connector and that one worked flawlessly.

I used engineering mode to disable the MB assistant, so now when I click the voice button I only get Siri (which is great).

The only complaint I have is that if the head unit is not on the AUX input, you have to switch back to the OEM screen, activate the AUX input, then switch back to the Road Top unit. It works, but is a bit cumbersome. I was wondering if there is a way to reprogram one of the head unit buttons to switch directly to AUX to avoid this? Perhaps like have the radio button to default to AUX first, and use the dropdown for radio (or maybe a long press function, etc)?

Since the Road Top box has a canbus interface I am a but surprised it does not automatically switch this (some of the other carplay add-on units do this already). Perhaps it does and I missed that in the instructions?

cadetdrivr

There are a couple options, none of them ideal, besides having to return to the Comand screen to select inputs.

1) One can return to AUX by pressing the DISC button repeatedly on Comand while using CarPlay. Here's the note from the MB Comand manual:

By pressing this function button repeatedly, you can change the operating mode in the following order:

• CD/audio DVD/MP3 (disc)
• Memory card
• USB storage device
• Media Interface or audio AUX mode
• Bluetooth audio mode

2) FWIW, we found that the only other input we were using was the radio and it turns out our favorite local stations were available via CarPlay compatible streaming apps with MUCH higher streaming quality than the 'HD' Radio broadcast. (HD stands for Hybrid Digital, not High Definition)

cadetdrivr

^ ^ ^
Just so nobody is confused by this ad, THIS DOES NOT APPLY TO THE 2013-2016 GL (X166).

This dongle only enables wireless CarPlay for those vehicles with factory installed CarPlay that used a wired connection..

NewCents05

i am selling my carplay box since i sold my gl if anyone is interested

canron

Hi Can you explain to me how you got the audio working without using the cable to the AUX.
I have a lot of noise when using the aux port and have no idea how to fix it.
Already thanks.

NCWolverine

You have to go in to the Engineering Menu on the Comand Screen, to enable it. Aside from the posts above that speak to it, this link was helpful in enabling it and also disabling Comand from the steering wheel button for Siri.

canron

Hi,
Thanks for the quick reply.
I already had the settings changed in the engineerings menu.
My problem is that with I cannot get any audio without plugging the line out cable from the CarPlay box to the MMI plug in the armrest.
in your posting you write you did not have to use the MMI plug.
How did you get that to work.
Again thanks, I battling with it for a week now.
So most probably I forget something simple.

NCWolverine

I'm racking my brain to remember the exact steps at this point.

I know I did have it going through the AUX in the armrest at first to make sure everything worked, but the thought of having to disassemble the center console had me figuring other options. There may have been a setup within the CarPlay software as well, but I'm not entirely sure.

If I can piece together enough recollections, I'll post an update.

NCWolverine

Sorry, one other question.

In addition to enabling the Audio AUX, you also disabled the AMI port? I recall having to bounce back and forth on this but cannot recall which setting I stuck. I also left the AMP set to Internal, unlike the video.

canron

Hi,
No idea why, but suddenly everything works.
Must be me playing around in the engineering menu.
I put the amp to internal, activated both aux.
Closed the car, got a coffee and when I returned everything was working without plugging in the aux in the armrest
Thanks for pointing me to the menu.

NCWolverine

Awesome to hear. When I got it working it was pure madness for a day or two.

Now if only I could figure out how to get the RoadTop to stop trying to connect to my wife's phone, once she leaves and locks the car.

ccrobin

Sorry, just saw your question to me, glad you got it all working. To be honest, mine is using the cable plugged into the AUX port in the center armrest. Are you saying you got it to work without using that cable plugged into the AUX?!?
Originally I used the adapter that came with the Road Top unit, but it was very poor quality. I had the Mercedes iPod cable with aux in and that one worked well. While it is working, I'd love to be able to eliminate the cable running to it.