ClayL

Arielsdv - thanks for the compliment and nice work finding the MVA-81 adapter. That looks like the holy grail solution if you replace the radio with an aftermarket unit. The only downside is that you will not be able to control the audio with the nav system as I read the audio button will be disabled. I am thinking that is not too steep a price to pay. Grasshopper, you have managed to snatch the stone from my hand and may now leave the temple.

Hello again and I have the penultimate solution!!! I installed the second used amp off eBay and it did the same thing! (No volume using knob or steering wheel volume control). Figuring it now has to be the radio, I ordered a used radio off eBay. It took some days to get it. Dreading the dash dissection, I plowed ahead fearlessly. Once the new radio was connected and the amp re-installed I crossed my fingers and hit the power. A sound of static filled the car! SUCCESS!!!! I of course tuned to the first station I could find and the Eagles came sounding in with Take it Easy. While I was waiting on the radio to come, I had called a service rep at Lexus. He said that if you replace the amp and you still get nothing, your next move is to replace the radio. I sent money to both of the eBay sellers for returning their amps, which were probably good. A fan on an amp that turns on for a second and then shuts off DOES NOT NECESSARILY MEAN THE AMP IS BAD. In my case it was the radio all along. After the radio replacement, all functions of the Mark Levinson sound system and Navigation system work perfectly.

Hi Arielsdv and Tinatank, I have the same dreaded GX470 no sound problem. Just replaced amp with eBay amp did not fix. Fan on amp spins for a second when key turned on on both original and replacement amp. I have ordered a second used replacement and I am waiting to install it. You probably also have these conditions: (1) volume indicator on audio screen does not indicate volume is being turned up (2) equalizer settings work perfectly when they are being adjusted, (of course as unit stays silent) (3) with amp removed, volume display not present, equalizer screen can be seen, but not adjusted and adjustment levels not indicated (4) fuses are good. To me, this implies that part of the amp is malfunctioning, and that the amp is ok otherwise because with no amp you get no option to change the equalizer settings. The maddening part is that it is possible that the replacement amp has the same problem. If my second replacement amp fixes the problem, I will be back to post the fix. I think it is safe to say that it has to be the radio unit or the amp. All I have been reading everywhere seems to suggest that there is somehow some mysterious wiring anomaly (gremlins) that is/are outside of what can be attributed to the radio unit or amp. I am doubtful of that but admit anything is possible. The fix will come when the volume display registers volume change when the knob is turned, which is what is not happening now. I am sorry my posting comes with no solution, but the sharing of this type of information may lead to some genius getting it solved.