About 18m ago our OEM head unit went into a boot loop… just the Mercedes Star… then blank, the Mercedes star.
I assumed the head unit had failed and bought an Avin 9” unit with all the parts for the correct install for our Harmon Kardon equipped setup.
I installed it, and it boots, looks great, but no sound.
I’m realizing I probably misdiagnosed a bad head unit when the problem is probably elsewhere.
I have no idea how to fix this.
Is it the Amp, the Sirius unit, or the phone module?
I’ve checked fuses, but where do I go from here?
I bought these little Optical bypass loops but they don’t fit.
Is there a diagnostic tool i can buy/use to pinpoint the issue?
Help!

 

Am I asking the right questions?
Is there a Diagnosic Program like Star that actually checks the Audio or Audio Components?

 

Star system would have been the route to go before tearing it apart. The amp underneath the driver seat is always a culprit for water and corrosion .

 

Agreed, but can you confirm that Star System or a clone, or some other diagnostic tool can read faults in the Audio system?
I have a Carsoft MB 2, and Autel, but don’t see any Audio related diagnostic info.
Id be ok with investing in more diagnostic equipment if someone can tell me what to get.

Assumed the problem was the head unit.
I could put the oem unit back in, and test if that’s the only way to go.
Didn’t cut any connectors, so wouldn’t be a huge job.

I had the drivers seat out, and checked the Amplifier visually… dry as a bone, no sign of it ever having been wet, checked its fuses etc.

 

I don't think Star will help you. I only say that as I've never seen a post that highlighted fault codes from the head unit itself.

If the original head unit wasn't booting up I'd be tempted to reinstall it but reduce it to the basics if you can - sound only. You'll probably need to unpin many of the wires from the large plug at the back, and add them one by one - or find another W164 and install it there and see what happens.

 

It's possible that the integration with the existing Harmon Kardon setup wasn't seamless, leading to incompatibility between the new head unit and the factory amplifier. Additionally, the wiring harness or connectors might not be properly aligned or secured, causing signal interruptions. The issue could also stem from the Sirius module or the phone module not communicating correctly with the new head unit, preventing audio output. Moreover, if the optical bypass loops you purchased don't fit, there might be a need for specific adapters or alternative wiring solutions to ensure all components are correctly interfacing. I would recommend running a full system scan to identify any fault codes related to the audio system modules. There should be fault codes stored in one or more control modules that could shed light on the underlying issue. You might need to take the car to a mechanic for this, but if you prefer to diagnose it yourself, the youcanic full system scanner is excellent for diagnosing all systems. Just make sure to use a full system scanner, as some tools might not read all vehicle systems and could miss important codes.

 

Thanks.
I was assuming that the failure of the original head unit was something in the system, but I just don’t know.
Which Youcanic unit are you referring to?
Or if anyone can recommend something else?
I’ve looked at getting a pc based Star clone but it’s super confusing…