I have a 2000 XJR with the premium Alpine system (cd changer, nav, amp in trunk). I can't seem to figure out which wires to check to make sure the radio signal is getting to the amp. There is an AINET cable, but there are also other plugs with lots of wires. I can't tell from the wiring diagram which wires are the AINET connector and which are the other guys.
The problem is that the CD player sounds great, but when I switch to radio, there is no sound. The radio tunes in stations and displays what is playing, but there is absolutely no sound. The AINET from the head unit goes to the nav system then there's an AINET from there to the amp. The CD player has an AINET cable that goes to the amp as well. I even ran a new 15' AINET cable from the head unit to the nav system in case there was a problem in the AINET cable, but it still doesn't work. I even bought a new (well, used) head unit, but it has the same problem. Should I be checking some wires to see if something is trying to mute the radio? (There's no phone installed. When I poke the phone button, it says there's no phone.) I'd just like to know how to check if any audio signals are making it to the amp. I've ordered another amp in the mean time.

 

@MrBern

Do you get sound out of the tape player ?

If you had a mute issue the display would show "Phone" on it, and you wouldn't get any sound from anything (including your CD Player, which sounds like it's working)

If you tune to AM do you not even get any static noise ?

All the sound signals from the HU go through the AINET cable as you described to the AMP. If you aren't getting anything from any HU source, it does point to the cable (but you already tried that) or the inputs at the AMP.

Did it used to work and its just suddenly stopped ? or it's never worked ?

 

I had a 'No Sound issue with mine. Radio still tuned in, and "SEEMED" to work, just No Sound... I chased wiring, pulled the amp apart, tested all the circuits, pulled the stereo apart, tested all it's circuits, and went as far as buying a replacement radio just to find the issue still existed. Come to find out, one of the wires that lead to my power antennae was not connected correctly. I could not believe that could cause the sound to stop, but as soon as I reconnected the wire, it worked!

PS: If you determine it is the radio, I've got a used one for cheap! :-) Great condition. I kept my original, but the used one I bought is actually in better condition.

 

I haven't tried the tape player (don't have any tapes). The Nav system doesn't seem to make a peep either. Turning up the FM or AM all the way only has a faint bit of static. It came this way when I bought the car a few months ago, and I've been trying to get it to work ever since.
SuperSport may be onto something. The used car dealer mentioned something about an antenna wire, but I didn't think much of it since the antenna goes up and down when I turn on/off the radio, and it seems to find channels just fine.
I would be very interested in where to look for that connection! Any ideas?

 

Strangely enough, it was a power wire that was in the trunk connecting to the Antenna motor. It was not the signal coax. My Antenna motor did not run up and down, so I checked the wiring. When I reconnected the wire, the Radio started working, Antenna Motor did not, but I had sound. I promptly replaced the motor and now all is good.