Head Unit Randomly Muting

[izzbo 10+ year member]

My head unit (Pioneer AVH-P4300DVD) is randomly muting itself while it is on. I have the mute wire hooked up to the mute wire of the GMOS-01 harness. The reason for the GMOS-01 harness is b/c the car came with built in bluetooth and OnStar so I want to retain those features along with the chimes. When the head unit is working properly (ie.. not muted) I can make a call using the factory installed blutooth and the radio mutes itself like it should so I know the mute wire is attached correctly. I did have this issue w/a previous GMOS-01 I had hooked up in this car but I had to return that one b/c it malfunctioned after 3 days of use and it was supplying power to the ACC wire at all times. I can get around this by turing off the auto-mute setting in the menu of the head unit but I would like it to work as it's designed if possible b/c the head unit is brand new.

My question to you guys is could this be caused by anything else other than the GMOS-01 being a bit flakey? If the remote wire was loose or connected poorly could this cause it or could another loose wire somewhere cause this? Could it be an issue w/the head unit itself? I guess I just need help with how I can troubleshoot this. When the radio mutes does the mute wire have voltage through it that I could check?

I did see other posts about similar issues on the forum but there were no resolutions posted.

Thanks in advance everyone,

- Jason

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[All_Logix 10+ year member]

IIRC, the mute wire mutes the HU when it sees 12v....could be the other way around I just can't recall, there is the possibility the remote wire is touching it, or that the mute wire is touching metal and grounding, giving it the right signal to mute. There is also the issue that many people have had problems with the pioneer AVH-4000 series, I would bench test the HU though, that will isolate it to the wiring or the GMOS module

 

[izzbo 10+ year member]

Thanks. I'm 99% sure the wires aren't touching b/c I soldered and shrink wrapped every connection. In terms of the 12V mute, does it need to see a constant 12V or see 12V once to mute it and 12V once to unmute it? I guess I'm what I'm getting at is can I use a multimeter to see if 12V is going through the line and if it is then I can say it's the wiring, not the radio? To bench test the HU all I need to do is hookup the 12V constant wire (yellow) and Ignition Accessory wire (red) to a battery and then see if it mutes, correct? Should I hook the mute wire up to anything?

 

[TheUnderFighter 10+ year member]

Thanks. I'm 99% sure the wires aren't touching b/c I soldered and shrink wrapped every connection.

I just want to thank you for doing a proper wiring job. Whether you're just a forum noob, or a noob to the hobby, it's still nice to see someone taking the time to do it right.