What is the function of the radio PWM lines?

[RBRx]

First off a little back story, I bought a blutooth audio gateway which takes 12v and just outputs audio with the intention of splicing it into auxiliary input on the stock head unit to which I succeeded "sort of". I did this in the middle of the night so I put my parking brake on to not disturb my neighbors with the DRLs and left assuming the surgery was a success... I get ready to take a trip to the store, set my tunes on, then release the parking brake and I get loud pop/buzzes out of the audio.

Image of what was done for those curious... http://puu.sh/oknjr/5c7ad88d3d.jpg

So 2 things come to mind of what may be happening~
A. I'm getting dirty power that gets filtered down the line inside the head unit.
B. Internal RF interference.

These are easy fixes but the problem is how are these two linked to the parking brake (Head unit has no populated wire for parking brake detection)? Also the PWM lines could be related but first I wonder is what is a radio doing accepting PWM signals.... Can anyone shed some light?


EDIT: Nvm I solved the problem yes it was dirty power so instead of soldering onto the 12v+ pin header I soldered it onto the internal 12v rail which has been filtered. After looking at the pinout again I never saw a DIM for the dimmer so that's what the PWM signal was for.

[Daox]

Glad to hear you got it figured out, and thanks for posting the answer.

[RBRx]

Glad to hear you got it figured out, and thanks for posting the answer.

Well it's not a complete answer it could be receiving bursts of other information like parking brake, dim, miscellaneous... Dont know for sure since I dont own an oscilloscope.

FYI for those adventuring inside their radio let it be known that the radio is always on it's 12v line is live when the keys are out of the ignition. You need to find a 12v rail that goes into standby on the radio but other than that the crappy deck has bluetooth now \/

[jackster]

My 04 Aveo has a used stock radio/cd player that I installed to replace the original that became "flubby" about a year ago.

Within the past couple of weeks it started acting up too, & I was beginning to think that it is a seasonal issue.
This time, the radio lights up when I start the car, but produces no sound.
Within a few blocks of driving it would sometimes come on all of a sudden, & sometimes not.
As I turned the car off, the radio would always come on for a split second if it was not already on.

Yesterday I discovered that the slightest touch of the parking brake would bring the radio to life every time, but leave the brake indicator light on very very faintly.

There's obviously some electrical relation between the radio's operation & the emergency brake lever switch & indicator light.

Getting the radio operational this way is a minor nuisance, but I have to wonder if some kind of short that seems to be causing this might lead to more serious damage or even fire.

Can anyone out there shed some light on what's going on with this?
Thanks.