Sorry for the "Noob" questions, but I have a '99 that came with a radio/cassette player. My hearing sucks, so I don't care much about audio quality. The stock unit was okay. My wife, however, wanted something she could play WMA CD's in. Wally World had such a unit. It not only plays WMA CD's, but will play WMA files from a USB thumb drive or a compact flash card. Woohoo! I bought two of them, and installed one (making the required adapter connections) in the family POS Toyota Tercel. It took a couple hours, including adding rear speakers and routing the speaker wires. Works fine, sounds good (even to my wife, who can actually hear things).
Then I set up the adapter for the truck and hooked it up. The unit equilizer/display indicates it's putting out, but no sound from any speakers. First I figure I got a bad unit, but I hook it to the Tercel, and it works fine. The OEM unit still works when I put it back in the truck too. I figure maybe the speaker wires are scrambled, so I start ohming out lines. Hmmmm, can't seem to 'find' any speakers that way either. I see 'open' on all pairs.
Next I start reading threads posted here, and find that there MAY be amps somewhere between the unit and the speakers.
Does the hypothetical amp require power from the unit? Do I just bag it, and replace the wiring to the speakers, bypassing said hypothetical amp?
I've been wiring things for many years, and this has me feeling pretty silly.

THX
Grider Pirate

 

my truck has the infinity system in it.it had crossover's on the speakers which i wired to some after market one's.i even hooked an aftermarket amp up off the rear speaker wire's,with out any issue's.i had the front seat's out and some of the dash appart,but never found anything that looked like a factory amp.i would think they would put it somewhere to get airflow.i don't think just the radio was powering the factory speaker's though.it would probably show something in a service manual,if you have one.
alot of time's there is some kind of convertor to help you wire an aftermarket radio.most of the time they help you bypass the amp.i would call a stereo place like circuit city or best buy.

 

or you could just run all new speaker wire.... or at least thats what i would do. i put a new stereo system in my truck but i didn't have any problems, however one of my dads old trucks had the infinity sound system in it from the factory and we had to rewire the speakers when he blew them out and we put a cd player in it.... good luck!!

 

If you have the Infinity dodge system you have amps on the front door large speakers. These amps send a signal to the speakers on that side of the truck (tweet, front speaker and rear speaker). From the stock head unit you will have signal wires to each amp and power wires to each amp. I haven't done it, but I read on this forum (you can too using SEARCH) most owners who replace the head unit also rewire and replace the speakers, and install better amps.

I guess that when you wired your new head unit you didn't send power to the amps, thus no sound.

 

In the instructions to the Sony unit I used to replace my Infinity it said to use the wire that normally powered an automatic antenna to feed the door amps.
I did, works great.

 

Watch your instructions though. I did like Infidel did on my 96, and found that the amp did not work on CD or USB. Turns out the deck was so "advanced" that it put the antenna down if you weren't using the radio function. I had to use the AMP output of the deck to get my amp to work all the time.
But yeah, one of them wires in the harness powers the amps (one in each door, attached to the speaker).

Chris

 

i have the infinity system just like yourself. when i replaced the head unit i didnt have any sound at all. thought the radio might be messed up so i plugged in the factory one. it didnt work either. turned out that there is a ground wire hooked to the back of the factory radio, to a screw in the case if i remember correctly. when i hooked this wire up to my aftermarket one, it worked like a champ.

 

i didn't think those where amp's attached to the speaker's.good think i put the splash guard back over them.