SWendell

I've read several of the other posts on troubleshooting this audio issue (Mark Levinson system on 2013 GS350). I had many of the same symptoms:
Initially a big pop. This was replace by an intermittent popping sound. Even the intermittent popping went away. So no sound from any source (even the tone when changing screens on the multi-display). The volume readout doesn't display when turning the ****.

After reading the other posts, I checked the trunk where the amp sits, and I had a cooler in the trunk that had leaked onto that spot. I pulled back the panels, and the amp was indeed damp. Tried air drying it for several days, but no go. Seemed like a smoking gun, so I bit the bullet and replaced the amp with one from United Radio.

But still no sound. I unplugged the car battery when I replaced it, but is there another "reset" button I need to hit? I checked two of the radio fuses under the passenger side panel, but they were good. On the ML amp itself, there is a red light that does turn on (that light still works on my original as well). So I assume it's getting some power, but possibly a different fuse?
Maybe I just got another bad unit from UR?

Not sure what my next step is here. Suggestions appreciated.

jgscott

iTrader: (1)

Maybe a bad unit, as its happened to a few ppl here before. Or the short from the Amp took out something at the Head unit also. Is everything non working symptom the same as the 1st unit with the 2nd one? The Head unit is the Source to feed the amp to drive a source.

SWendell

Yep, they both work the same now (which is no sound at all, no cracking, no popping).
It's not required that I fully mount the amplifier to test it right? In other words, the screws themselves don't provide a required ground?

LeX2K

Doubt it but verify anyway by temp running a ground. Sounds like you got a bad replacement amp though.

jgscott

iTrader: (1)

Could be that car the amp came from was hit in back or something that damaged or let water in. I would ask for another one.

mcerot

Bro if one of your speakers is shorted out, you will get no sound but everything will be on. I’d check the speakers up front - the center channel especially because **** surrounded by metal.

SWendell

The issue did get resolved. I got support from the seller. He originally had two theories. I'll paste the full response.That further confirmed a fuse wasn't my issue. But I was also hesitant to start tearing into the center console to clean a connection when I was pretty sure I had the original cause (not that connection). Once I talked to him on the phone, and explained that to him, he attempted to walk me through a test. We checked the consistency of the voltage on the white wire of the connection clip farthest to the right (when installed and viewing from inside the trunk). Since it was consistent voltage, he determined it was not the junction under the console, which probably saved me at least half a day slowly pulling that apart. However, while doing that test, I was fidgeting with the connector itself, and that resolved it. It was just a bad connection between that connector plug and the unit. I sprayed on some electronic cleaner and worked it in a few times, and all has been good since then.

Oddly, he still didn't think my issue with my original amp was because of the cooler leak. As alluded to in a number of other posts, he thought the vent to the outside was more likely the root cause, and suggested it might even be better to tape it shut. I haven't yet decided whether I'll do that. It's a very confined space and that amp already gets EXTREMELY hot. Maybe there is a hedging solution in there somewhere.

jgscott

iTrader: (1)

Good its fixed. What vent to the outside?

peasodos

iTrader: (1)

The vents in the trunk. This acts as a check valve to relieve air that is delivered into the trunk compartment from the passenger compartment to the exterior of the vehicle.

122k miles and I never had any issues with the ML amp.

SWendell

Here is a video of someone replacing that vent (his was an IS350), so you can get a good look at it. In the video, it looks like the vent just drops onto the ground. I'm not sure mine has that same direct access to the exterior.
He is replacing because of shrinking of the foam rubber flap which created gaps around the edges. Mine didn't have that issue, and still closes fine.
When I spoke with the seller, he mentioned Lexus updated this part, but he still wasn't confident with it. The new part # is mentioned in this video.

I was thinking it was to allow at least some amount of cooling from the outside, but it sounds like that's not the primary function. Interesting on the check valve... I guess I hadn't thought about that before. If the passenger area was completely sealed, the climate control system would have a hard time delivering air, so that makes sense. And that means the amp may get some A/C benefits of being in that path of the airflow.

peteharvey

I had to take mine to Lexus.
They exchanged it for another OEM Pioneer unit for about $500.
There may be absolutely nothing wrong with your amp.

NebulaGrey

had my audio go out on me today - no volume and no visual volume adjustment when turning the ****...... searched and did the same as above and the volume came back. had no water leaks or spills - red light on amp was still on....

NebulaGrey

audio went out again. The only way I can get it back working is if the car is on and I unplug/plug the power harness to the amp. Audio stays on until I turn Off the car. A hard reset (holding down the volume button for 3 seconds) didn’t work either.

wfibear

This is the exact same problem and solution/workaround I'm having with my ML amp. About a month ago there was no audio when starting the car 2 or 3 times, then it was fine until this past Monday. Now pretty much no audio at all every time unless I do what you did (pulling the power from the amp while the car is on, and plugging it back in, which seems to work consistently). The audio will be fine until the car has been off for a significant amount of time (like 30m+). Again like yours, rebooting the head unit via volume **** doesn't fix it. When there's no audio, the amp does appear powered (red light) and turning the volume **** does reflect a change in volume, on the screen at least. Still no audio.

The thing with these amps is they aren't dumb devices like they were a couple of decades ago; they communicate with the head unit via a bus called MOST (kind of like Ethernet for automotive multimedia) and the audio they get from the head unit is a digital stream, so by design they have to have some level of computational ability. What this sounds like to me is the computer side of the amp isn't initializing correctly when the car is started. Unfortunately I imagine that means something is failing and off to United Radio it'll have to go...

Cwang

That's easily sorted. You just need a relay that opens the correct wire when you just in the car.
You could have it on a toggle switch in the dash (even OEM if you could BF)
You could have a positive edge trigger engaging a 556 timer that opens the relay for 5 seconds, so you won't have to think about it again.