Been working with this USA SPEC PA11-GM 45

Re-read -- https://ls1tech.com/forums/wiring-st...t-adapter.html

I hear fairly low a classic engine whine, and louder a weird sound I can't describe at times, especially when the ipod is not playing but when switched to the aux channel.

I think that's the CD/Play button, I forget. With the USA Spec adapter connected I believe it senses the iPod and jumps to the aux input.

But anyway, referring to THIS "You will need to have your CD player playing for this to work, even though it's using audio from your MP3 player. I know some of the aftermarket adapters that plug in between the HU and the cd changer work the same way, the changer plays, but it replaces the audio."

Is there some kind of signal that you need for the left & right channels and/or the radio amp to switch on?

Is that why the CD player must run?

I'm wondering if that signal is the weird sound I hear that's louder than the typical engine whine (grounding loop issues) ?

Again, these sounds are many times worse when there is no or a low signal from the iPod.

All this effort because the OEM radio is 1.5 DIN and I like how it looks, especially at night. lol

Not overly interested in cramming a 2 DIN radio in...

 

I think you may be mixing two different options for auxiliary input. The do-it-yourself modification which wires an auxiliary input to the wires inside the CD head unit requires a CD playing because the HU won't activate the signals on the spliced wires unless it "sees" the CD player running.

The external adapters that plug into the CD changer port on the back of the head unit do not require anything of the head unit other than being a compatible model (any year cassette head unit and 2000-2002 CD head unit). There was one from PAC which required the optional factory CD changer to be installed even though the changer was unusable with the adapter connected but it did not require a disc be running. The other brands (PIE, USA-Spec, etc.) didn't care if you had a changer as long as your head unit was compatible with having one. The adapter faked the communication that the factory changer would provide so that you could use an auxiliary input and the head unit would see it as a CD changer.

 

Hi,

So that "communication," what is that exactly?

Is it some kind of signal to tell the radio amp and/or the left & right channels to turn on?

Would you think you could ever hear that communication signal at lower volume levels?

Do some of these cars ever need ground loop isolaters installed on the power or speaker wires to eliminate noise in the Monsoon radios?

I'm no expert, but I remember reading before that certain aftermarket parts or maybe defective parts in things like the alternator can cause these types of noises, and if you can't find the exact cause sometimes an isolater will work to eliminate the noises?

I remember I had two large d-cell looking things on my old Kenwood radio's power leads in a car that fixed this type of issue.

They were so large it was hard to find space for them in the dash. lol

I have to do more testing to see if you hear these noises on the radio, or only when using the USA Spec adapter.

 

The communication is serial data and not something you would be able to hear through the speakers. It is used to determine that the optional CD changer is installed (otherwise the changer controls are disabled) and for sending function requests such as disc and track changes from the head unit to the changer.

Under normal circumstances, you should not need any kind of noise suppression for the stereo system. Aftermarket accessories can cause noise and some electrical defects can cause noise. For example, a bad alternator can cause a whine which will vary by engine speed. If the underlying cause of the noise can't be found or corrected then power filters can be quite effective at reducing or eliminating the noise.

 

Thank you SO much for your patience with this and all of the help!

All the above you wrote was VERY helpful.

I had a little time to play with it today.

The whining and the other noise seem to only be heard on Aux/Play, I don't hear these noises on the radio -- so weird.

I tried unplugging the USA Spec at the white box part of it, I could still faintly hear the noises but not as loud.

Is the little CD on the display supposed to mean a CD is currently loaded? Nothing is ejecting.

While I was tinkering I saw error 33, what is that error? Will try searching on here...

I think on Aux/Play I may hear the CD deck spinning, is it supposed to make a faint ticking noise?

What fun!

 

I found this --

http://www.hummerknowledgebase.com/acc/msec.html

Might have just been from my tinkering?

 

Nice to see how they copied my list of errors from the Monsoon FAQ sticky at the top of the section .

It certainly seems like the error would be related to the adapter you've connected to the CD changer port. There could be multiple reasons that the adapter caused the message but if it doesn't happen often then I would just ignore it.

 

Is the little CD on the display supposed to mean a CD is currently loaded? Nothing is ejecting.

UGH! "Nice to see how they copied my list of errors from the Monsoon FAQ sticky at the top of the section ."

I knew it was here somewhere - search here was not finding, so I Googled...

 

The little CD icon indicates that the CD changer is attached. In this case, it's because your adapter is mimicking that a changer is attached in order to make the head unit port active.

It was nice that the Hummer site referred to us as "the F-Body site".