Problems while installing car stereo.....help!

[TAvsGN]

I am trying to install a Kenwood KRC4003 into my 77 Grand Prix. It is a shaft style cassette receiver. I have been having a couple problems throughout the install. First off, when I was wiring for the power, memory and ground, the unit would not power on. Power wire was to a switched source in fuse box, memory to an unswitched source and ground was to the metal dash frame. No power. I was using a test light to check wiring and accidentally hit the radio chassis. The unit flashed on, and when I grounded the actual chassis of the radio, the unit would work. I also noticed that when I mounted the rear mounting brace to the dash frame, it would also get power. So I wired up the speakers according to the manual and checked it again. Its getting power and holds memory, but no sound to the speakers. I pulled the unit out to go over the wiring and now it did not need any type of chassis ground as described above, it stayed powered. The manual describes a BTL hookup for a 2 speaker application; left front positive and left rear negative to the left speaker, and right front positive and right rear negative to the right speaker. I used the old stereo wire diagram to tell me which wires from the car go where. I then took the speaker wires apart. Since I did not do the old install and I am not 100% sure of the wiring, I tried a set of speakers that I had laying around directly off the new radio wires. Same hookup as the manual called for...no sound. I even tried both left rear wires to the same speaker, etc, and still nothing. I can't figure out if I am missing something or if there is a problem with the radio. Everything worked with the old radio too. I already have a Kenwood KRC2007 shaft style in my 78 Formula and really like it, so I would really like to make this one work. Just hoping I don't have to end up having it fixed. I hope this explanation makes sense, if any clarification needed, just ask. Any help would be appreciated. Thanks!!

[PaulD]

sounds like the ground wire going into the radio is suspect.

there may be a physical switch somewhere that turns the internal amp off.