ClubLexus - Lexus Forum Discussion - No audio or volume control. What's the problem?

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No audio or volume control. What's the problem?

UPDATE: ISSUE SOLVED, scroll down to see what the issue was.

2015 GX460 owner here.

I installed the Beat-Sonic LGVIF-CB4W Carplay unit yesterday, and it worked for about a minute and then started cutting out. At first, I thought it was the wifi signal, but after connecting via USB, the problem continued. After another minute of wiggling wires trying to find the culprit, the audio cut out completely. I removed the Beat-Sonic device and reinstalled all the original wire harnesses to the stock configuration. After triple-checking everything, I still do not have audio.

Here's the list of symptoms:

No audio from any source (FM, AM, Bluetooth, CD, AUX, etc.), despite all of the sources displaying on the screen and functioning correctly.
No volume number is displayed on the screen when using the volume knob or the steering wheel.
No audio from cell phone calls.
No audio from the navigation.
No "beeps" when pressing system buttons.
No audio from the seat belt alarm.

Here's a list of things I've done to troubleshoot:

Pulled and checked all the fuses, and they look fine.
Disconnected the battery for 10min, then an hour, then overnight.
Disconnected everything and inspected all the plugs and pins; everything looks good.
Entered the secret service/diagnostic menu and ran a system check, and everything returned OK.
Entered the secret service/diagnostic menu and confirmed that the radio unit is receiving signals from the steering wheel when buttons are pressed and from the volume control knob on the radio unit.
Called Beat-Sonic, and they were accommodating and pointed me in the direction of a cable or connector issue as they have seen similar in the past. No luck so far identifying the problem.

The closest thing I've found to the same issue is this post on ih8mud from a 200-series Land Cruiser owner. It seems the problem was a faulty cable connection.

Questions for you guys:

If the problem is most likely a cable, which one and which wire? I found this pinout diagram link, and it seems pretty accurate.
If the radio unit is properly receiving volume commands, why isn't the volume change showing up on the screen? Could the visual display of volume somehow be triggered by the actual volume changing?

What steps should I take next, guys? I'm completely stumped and don't know what to try next.

UPDATE
I spoke with the service dept manager at Lexus today, and they recommended having one of their master technicians look at the issue. They said the fee to diagnose the problem would be $220, whether it took 8 minutes or 8 hours to pinpoint.

I've got some micro needle probes coming for my multimeter today and will start trying to troubleshoot the issue myself before I go the Lexus route. If anyone has heard of this issue before, any help or tips would be greatly appreciated.
Thanks,

Since you mentioned there is no audio for any sources and no volume indicator, it seems there is no feed into the amp, and your head unit functioned OK. As you unplug and put inline BeatSonic unit, have you checked if the Audio connector, I believe it was an 8 or 10 pins white connector, that is feeding the pre-amp signals to amp, if that one has been damaged, such as broken pins?

Quote:

Originally Posted by hzhao (Post 11441899)

I've removed all the BeatSonic devices and cables, so everything is back to stock, and I still don't have audio. I checked all the cables and pinouts and they all look fine.
I'm really at a loss for what this could be.

Quote:

Originally Posted by 29er (Post 11441944)

In worst case, you may have a malfunction Amp unit. Did you check the fuse for the amp, also check under the passages seat, if amp is getting power or if it is working.

Quote:

Originally Posted by hzhao (Post 11441971)

In worst case, you may have a malfunction Amp unit. Did you check the fuse for the amp, also check under the passages seat, if amp is getting power or if it is working.

It's the Mark Levinson system, so I believe the amp is in the back of the vehicle on the left, right? Unless there's another amp I'm not aware of.

Quote:

Originally Posted by 29er (Post 11441976)

It's the Mark Levinson system, so I believe the amp is in the back of the vehicle on the left, right? Unless there's another amp I'm not aware of.

You are correct if you have the ML system. Are all fuses OK? And Amp is powered up?

Do you know how to use a multimeter?

Quote:

Originally Posted by evilfij (Post 11442206)

Do you know how to use a multimeter?

Multimeter is fairly straightforward, especially today’s digital ones. In principle, there are two probes for the meter, one is ground, commonly marked as “Com”, the other will be the probe point. Depends on what you trying to measure, you select the the value for your purpose on the meter. For example, to measure the power, you select voltage within a proper range, some multimeter has the auto range for easy use, others has selected range such as up to 6v, up to 60v, etc. also make sure to select DC instead of AC since car power supply are all DC based. If you want to check particular pint to point continuity, you just select the Ohm (Ω). Those are some basic references for using the multimeter.

Quote:

Originally Posted by hzhao (Post 11442001)

You are correct if you have the ML system. Are all fuses OK? And Amp is powered up?

yes, the amp is powered up and all the fuses are good.

Quote:

Originally Posted by evilfij (Post 11442206)

Do you know how to use a multimeter?

yes, I have a multimeter and micro needle probes to test the tiny pin outs.

I didn't get to use the multimeter today, but I did plug in my OBD2 scanner and got this DTC code: B15D0
This is what the error means:

The MOST network cannot be established after the master unit is activated.

If a short occurs in a speaker circuit, the sound from the corresponding speaker will be low or almost impossible to hear. If the volume is turned up in this situation, to prevent excessive current flow due to the short circuit, the stereo component amplifier assembly stops operating when its output exceeds a certain level. When the operation of the stereo component amplifier assembly stops, the navigation system will not function normally. This is because MOST communication will stop due to the shut down of the amplifier causing an error in the MOST network. The stereo component amplifier assembly will start operating again when the power switch is turned off and back on (ACC) again. However, the amplifier will stop operating again if its output exceeds a certain level.
When the stereo component amplifier assembly stops operating and a malfunction occurs in the navigation system due to a short in a speaker circuit, this DTC will be stored.

Trouble Area:

MOST line check
MOST communication line connector
MOST communication line
Television display assembly (w/ Rear Seat Entertainment System)
Stereo component amplifier assembly
Multi-media module receiver assembly

So, that doesn't help me much, but if you know more about these errors, I'd love to hear it.

To make it even more interesting, the self-diagnostic test reports the MOST network is OK.

https://cimg8.ibsrv.net/gimg/www.clu...77dbdbe317.jpg

Yep, found that too.
Looks like me and my multimeter are gonna have some fun today.

Is it a single line-out to the amp or is there one for each speaker? I’m thinking pinched/damaged wire given it was intermittently working initially. Sorry this happened, good luck!