Just for background, I'm setting up a carputer similar to ITL's.

I intend to maintain the factory radio in-place, for cosmetic reasons as well as maintaining bluetooth HFL capability. As I am not using the factory head unit to source anything but audio from the HFL, what I'd like to do is (if necessary) wire either the left or right speaker output from the factory amp to the otherwise un-used factory center channel speaker, thus maintaining an audio channel for HFL via the factory setup.

What I'm wondering is, is there an accessable wire anywhere in the factory install that goes "hot" only when the HFL goes active? My idea is to use a relay or some such to cut off the remote signal to my aftermarket amps when a bluetooth call comes in on the factory HFL system, thus muting my aftermarket sound while I take the incoming call via the factory HFL.

 

There's a wire that the ETM lists as "HFL Mute" that goes between the HFL Control Unit and the Audio Unit. No details are given concerning it's operation (active-high?, active-low?, is it even being used at all?), but it's the only likely-looking candidate that I can see since pretty much everything else is network communication over busses (no dedicated wires for any functions).

It should be a Blue wire with Red stripe on the 26-pin connector at the back of the Audio Unit. If you have '04, it should be position 16 on the connector (3 in from one end) -- if you have '05-'06 it should be position 20 on the connector (bottom center).

(Disclaimer: I'm simply regurgitating information from the Helm's Electrical Troubleshooting Manual. I have no idea if this information is accurate or not.)

 

Thanks! That sounds like exactly what I need to make this work. Now, all I'll have to do is hop on that wire and see if it gives me a feasable signal, then figure the best way to use that signal to mute my audio system when a call comes in.