voltage drop?

I have a 2000 Monte Carlo that I just bought, and the aftermarket deck just went out all of the sudden. I checked all the fuses and everything was good but when i checked the 12V switched power it had dropped to 3.2V's. I traced the wire and checked where the spliced wire leads to to in the fuse panel and see no problems. I hooked the deck up to the constant 12V and it works, but most of the switched wires on this car are 14v and 15v and the deck wont run on these high voltages. Any suggestions or ideas.BoboBeware

I'd be surprised if the deck does not run at 15V - most should be rated for up to 16V. And 14V is a common vehicle voltage - how could any 12V unit NOT handle that? Why do you say it does not handle those high voltages? Its paper rating? And rotate or swap your fuse. It could be an intermittent fuse, or a bad connection.

The unit itself wont run on a higher voltage ( not that great of a deck) but my big problem is the lower voltage on the 12v switched wire. I checked the auxiliary power drop under the glove and it has the same low voltage around 3v's. Bad Ground? Anyone have a wiring diagram for a 2000 Monte Carlo?BoboBeware

The power supply on my bench STAYS at 15 volts.  I have never had a radio that would not turn on at that voltage.  There is no switched wire in the OEM radio harness.  That is why they ran it to the fusebox.  You need to use a meter and check every fuse in the fusebox.  Chances are you have a blown one somewhere.  If you can not find the blown fuse, how about using a relay triggered by one of the 15 volt wires to provide power to the switched wire, using the constant wire as a feed for the relay?

Ground to 85

15 volt wire to 86Constant to 30Radio's red wire to 87

I did some more trouble shooting and it seems the installer taped into one of three wires. I checked all the fuses and the three fuses being affected are the BCM, windshield wipers, and my Cigarette/Aux port are all at only 3V's and because of this are not working. Any help or again a wiring diagram of the car would be helpful.BoboBeware

Probably a fusible link, usually in an electrical relay/fuse box near the battery. (I don't have any other relevant information. Owners Manuals usually indicate where fuse/relay boxes are.)

No luck on the fusible link can't seem to find it, its mentioned in the owners manual but doesn't specify where exactly it is. Still looking for the solution and thanks to everyone for all the help.BoboBeware

Turned out to be the ignition switch. Traced the problem to the ignition switch and replaced and problem solved. Thanks for the all suggestions.BoboBeware