New twist on old ML amp B15C3 ?!#?
 

I'll try to quickly explain.

Had b15c3 issue, stereo on but no sound coming out. It would be random. The car was a pre-owned and I thought that I have noticed a buzzing in the front driver woofer and maybe a bit of scratchy buzz coming from the driver front mid-range but it could have been my ears, I am not that young.

Went on a long road trip from GA to MD and back over a 5 days, never had the issue. Assumed there was some capacitor or something inside the amp that got fully charged so I replaced the battery. Worked great for about a week and a half then it started again. My battery reads 14.15 while running.

Strange thing is, I have noticed that if and when it works (mostly does)... when I leave for work in the morning, it will work, then after I park it for 12 hours, the inside of the car is HOT, it sometimes won't work, then after driving back home (20 min drive), I turn the car off. Use the FOB to lock it, then unlock it... it will magically work.

Which takes me back to thinking it has something to do with the battery or charging system or some sort of 'thing' in the amp.

Sent it into United Radio and got it back on Friday. They called and told me that it was defective when they received it but after taking it apart, it fixed itself (self-healed). so they sent it back...

Would an actual "short" in the system (outside the amp, like a buzzing speaker) cause this issue then magically be fixed after a short 20 min drive?

I do know that my 09' Porsche Cayenne had a similar very rare issue of no sound and I would open the door, close it, lock it with the FOB, unlock it and it would work. I am sure the Porsche techs told me about that but I can't remember.

Any ideas?

Thank you!

I think a short somewhere could cause the condition you describe. But the unit needs to be professionally diagnosed and repaired. Not sure where you can get that done, if anywhere. This day and age, radios are replaced mostly and not repaired, at least in the US.

You could maybe go to radio installation shops and ask to see if they would take it for diagnosis.

Radio install shops don't really do any factory amp repairs inside on the board for the most part.

I know who United Radio is, They have been fixing Lexus amps and other cars for many years. Unfortunately many have said they are not what they use to be, and kind of just run units in and out and don't do as good bench testing and repairing as they use to do.

I highly doubt the lock unlock has anything to do with it? Heat cool maybe? Has it fully worked at all times since you got it back from United? If not your choices are someone like the guy on the IS forum to repair. Or you can find a replacement used amp on ebay. There are other threads on CL in all models with this same problem both the ML and non ML.

Two of many below:

https://www.clublexus.com/forums/is-...r-failure.html

https://www.clublexus.com/forums/ls-...pair-tech.html