Expert: Ernesto R - 2/21/2010

Question
I am trying to install a jvc kd-vxd77 in a 1994 Chrysler lhs
I purchased the adapter plate and adapter plugs from my local stereo shop and followed the wiring diagram closely and that is when i had the problem that the sound was fine with radio only and with an ipod, usb, cd or dvd i would not get any sound although the counter on the display showed that the song was indeed playing.
i removed the stereo and hooked it up on the bench and tried it that way to double check all connections and i had sound on all 4 speakers with all types of inputs.
I plugged it back into the car and tested all my power leads and ground wire and they were all fine, but still no sound in the car except on radio.
then I tapped into one of the speaker wire sets while it was hooked up in the car and tried an external speaker and I got sound.
I again took it in to the garage and hooked it up this time with all 4 speakers and tried all sources and got sound on them all.
is it possible that the stereo uses a different speaker hookup configuration when using any source other then the  radio ?
I am also researching into a wire schematic for the car. I am wondering if it switches to a 4 wire to a 3 wire hookup ( 3 wire being left pos , right pos, and a common ground ) when using a source other then the tuner and when you use the tuner it changes to 4 wire  ( left pos, left neg, right pos and right neg ) ?
I am not a novice when it comes to this type or stuff but this has me totally baffled.

Answer
this is a very simple fix, just use the blue wire from the new radio to turn  on the factory infinity amplifier, you also need this interface , if you don't want to burn the factory amplifiers with the new high power radio ,if will play now but will get damage in a couple of months

http://www.oemautosound.com/pc-598-148-oem-interface-differential-converters-uni...