I’m experiencing a strange SYNC 3 AUX audio issue and was hoping someone might recognize this behavior.
This happens only with AUX audio coming from an aftermarket Android head unit.
All native SYNC 3 audio sources (radio, Bluetooth, system sounds) work perfectly and are fully synchronized.
Setup:
Ford Mondeo / Fusion with SYNC 3
Android (Phoenix) head unit
Audio routing: Android → SPDIF → Ford-specific audio interface → AUX into SYNC 3
Issue:
Stereo sound is present
Audio first plays from the left speaker
After about 1–2 seconds, the right speaker starts playing
This happens consistently when a new audio stream starts (e.g. Google Maps prompts, new app playback)
Important detail:
If I reselect the USB AUX source in SYNC 3 while audio is already playing, left and right immediately become perfectly synchronized.
As soon as a new audio stream starts, the delay returns.
Tried already:
ACM reset via FORScan
APIM / SYNC 3 reset via FORScan
SYNC 3 factory reset
No change.
Question:
Has anyone seen SYNC 3 handle AUX audio like this?
Could this be related to AUX stream initialization or DSP buffering?
Possibly specific to digital (SPDIF/USB) audio converted to AUX?
If this is MP3 audio, check for mono coding or joint stereo. Ideally you want 2 seperate stereo channels, not the previous two. Test your material on other source inputs to verify. If streaming, check the stream data for format compatibility with the downstream converter.
What is the Ford-specific audio interface? Obviously just a D/A converter…make sure it is set to the proper stream specifications and not decoding in an automatic mode.
This is most likely an encoding issue rather than decoding from your description. Decoders typically are passive and follow the encoded streasm information. Sync 3 hardware would not be the issue here since it is analog. If the Ford-specific audio interface is probably the place to start looking. If possible, connect it to a computer with SPDIF outputs and see if you can recreate the issue. Also, connect the Pheonix head unit to another SPDIF receiver to test.
I have seen this behavior in computers, specifically in RealTek SPDIF outs of the computer, where the digital output is muted or the laser is turned off if no music is playing. Makes the computer useless for audio editing.
If the Pheonix head unit has analog outputs, you could use those. You could prove the AUX input to Sync is correct also.
I would like to clarify the setup and the current behavior in more detail.
Audio setup:
• The Phoenix unit has a single audio output labeled COAX (RCA).
• This COAX output is connected to a small S/PDIF converter box, which converts the RCA signal to USB.
• The USB cable from this converter is connected to the SYNC 3 USB/AUX input.
• In other words, the entire audio stream from the Phoenix unit is fed into SYNC 3 via the USB AUX input.
Audiobox clarification:
• There is a second small box, referred to as the audiobox, which is connected inline with the APIM interface cable.
• Initially, I received the wrong audiobox, labeled Shevy / GM.
• With this box installed, audio was only coming from one speaker.
• I was informed that since my vehicle is a Ford, I needed a Ford-specific audiobox.
• I received the correct Ford audiobox this week and replaced the Shevy/GM unit.
Current behavior:
• After installing the Ford audiobox, audio now plays through both left and right speakers.
• However, the audio channels are not synchronized:
o When a new audio stream starts, sound first plays from one side and the other side follows with a delay.
o If I reselect the USB AUX source in SYNC 3 while audio is already playing, the sound immediately becomes synchronized.
o As soon as a new audio stream is started (for example during startup or when a new app starts playing audio), the left/right synchronization issue returns.
So in summary:
• Wrong Shevy/GM audiobox → audio from one speaker only
• Correct Ford audiobox → stereo audio, but left/right out of sync at the start of each audio stream
• Reselecting USB AUX temporarily fixes the issue until the next new audio stream begins
I hope this clarifies the setup and the issue more clearly.
So actually you are using USB to send audio into the APIM. It is likely the ‘audiobox’ unit is not syncing correctly with the APIM, or not using the correct AVSB codec/timing for the APIM, or is incapable to do so. Connect your phone via USB to the APIM and test the connection, if it works normally the issue is with the ‘audiobox’ unit.
Also, to clarify, in Sync 3 there is no AUX connection available externally, this is actually a connection thru USB. Sync 2 would use the AUX connection for analog audio, and USB for the digital connection.
From the look of the plugs on the cables the box runs on 120V. Is this correct?
Also, the USB connections look to be the rear USB connection for the APIM. Unless this box is a USB hub and is permitted in the Sync firmware it will likely not work, and if it does probably not properly. It would need to be connected through the Sync USB hub to be recognized properly by Sync.
Who manufactures this setup? Certainly not Ford…
This is a SPDIF signal over coax. Same thing as optical, different physical format.
This conversion must be configured correctly for the destination, in this case USB audio using the proper codec for the destination.
Using Bluetooth between the Pheonix and Sync would likely work much better.
From the wiring, the audiobox appears to be powered from the vehicle harness (two-wire supply in the APIM loom), so it is almost certainly 12V automotive power, not mains voltage.
The manufacture is Phoenix automotive it’s a 13.6 inch screen with integration of existing Sync 3.
Looks great but at the moment cannot seem to get it to work as they designed it while there are other people that do not have this issue. Looks to my as a hardware issue on there side. And indeed what they did is using the USB on the back of the APIM as sound in and the USB of the original HUB is fed into there USB unit so you keep the USB hub working through there system.
Still working with them on a sollution but i try to understand from a technical part how this works and speakers get out of sync on start or when switching a audio stream on there unit.
Phone works just fine. always used this last year.
See attachement for the other “audiobox” that is connected to the APIM loom. This was the wrong one (shevy/gm) that only output sound to 1 speakers. Now they send me a “Ford” one that gives me the current issues. So i dont know excacly what this box is doing. has a small print inside.
Depending on the firmware loaded on your APIM this will or not work. They use the latest firmware to design and test against, most likely. Over the firmware generations, changes to the allowed hubs have been made in Sync. I don’t know if this might be your issue gut it might be worth it to check.
Today got a reply from there support department. I had to enable setting below on the unit. this was disabled from factory. now the sound is working as should.
