no audio from radio; 92 camry wagon

[hoffmanbike]

about 5 months ago my radio stopped producing sound; it still lit up and was fully functional except for the lack of audio. or so i thought, now i've finally boght a new head-unit. when i went to plug this new unit in i experianced the same issue, no audio whatsoever.

the first head-unit (that i thought was bad) is a pioneer deh-4600mp. the new HU is a pioneer deh-5000ub.

since neither of them are outputting sound i assume it's a problem with the cars internal amp (the wiring diagram says that there's one) i've checked the fuses multiple times, all the wires that i have easy access to are intact. does anyone have an idea of what could cause this? my best guess at this point is the supposed internal amp. is it located in an accesible spot? how can i test it? what will happen next episode?

i used a wiring harness to hook up both the pioneer head-units. i did it myself (without instructions) but my process is similar to the instructions available here: http://www.installdr.com/InstallDocs...PDF/869013.pdf

[96paseo]

Take a volt meter and make sure the amp is getting 12V. I gather from what you've said that there's an amp other than the head unit. Have you checked the fuse/relay box under the hood? Fuses for external amplifiers are usually located in the box near the battery. If your getting power to the amp but no sound, make sure your getting signal from the head unit. Set your meter to AC volts. You should be getting 2-4 volts on the signal wires. Just make sure your playing a CD or have the radio turned on. The amp should be near the spare tire or behind the plastic moulding in the cargo area. Also, make sure your speakers are still good. If you still have the stock speakers, you may want to consider upgrading them. The surrounds on the cones may be dry rotted at this point.