Car Stereos: no sound from speakers, hyundai santa fe, sony cd player

Question
My wife has a 2004 Hyundai Santa Fe with the monsoon system. I put in an Sony CD player with a PAC OEM-2 wiring harness for the factory amp that is under the front passenger seat and everything worked fine and I had sound from all speakers.  The next day I was going to install an aftermarket amp to power a sub.  Before I started I turned the car on and the radio came on but no sound from the speakers. I tried my ipod, cd, and tuner but no sound, not even static.  The equalizer graph shows that music is playing.  The radio and amp fuses are not blown, mute is not on, fade and balance are set correctly, etc... I installed the amp for the sub and still no sound.  I disconnected the remote turn on wire to the amp in case it had a short and still nothing.  Any help would be appreciated  

Answer
Hi Chase,

Sorry about the delay in answering your question.

When you connected the after-market amplifier to your head unit, did it power on?  Did you get any sound from the subs?

The Monsoon amplifier needs to be activated through a remote wire, just like an after-market amp; so the first thing I'd check would be the remote connection.  The factory remote wire should be blue with an orange stripe; this should connect (through the adapter harness) to the blue/white wire from the Sony deck.  The PAC OEM-2 interface has an input and output wire for the remote connection, so it's possible that your deck's blue/white is connected to the PAC unit's input, and the output from the OEM-2 is connected to the Monsoon remote wire.  If this is the case, I'd bypass the OEM-2, and just connect the stock remote wire directly to the head unit's remote output.  This removes one possible trouble spot, and it's really not necessary to run the remote voltage through the interface.

Beyond that, your best option is to do some testing with a digital multimeter.  With this, you can verify voltage on the remote output, both at the head unit and at the amplifier.  You can also set it for AC voltage, and check for an audio signal output at the head unit wires, then at the OEM-2's output wires.  Any audio signal will show on a multimeter as a varying AC voltage, increasing as the music volume goes up.  (It's helpful to have another radio playing nearby, so you can tell what you should be hearing).  Basically, if you can verify that you have an audio signal going into the factory amp, and DC voltage on the remote wire, then a lack of output indicates a bad stock amp.  If I had to guess, though, I'd say there's either a problem with the deck's remote output going to the Monsoon amplifier, or with the OEM-2.

Hope this helps!

Brian