Installing Deck in ’92 Taurus

i just looked at a wiring diagram and the dark blue isnt used for anything, the wire with the clip on the end is the volume controls.

first off as you probably already know, you're not gonna be able to use those separate volume controls that are mounted up near the gauges, with this new JVC head unit.  Some of those extra wires are undoubtedly for this control (at least 3 of them since if I remember correctly there's the volume control, and then two separate buttons).  Just make sure that you tape each one up individually and don't make any connectiojns to it.

Same thing goes for any of the illumination wires that were not used.  Actually while I'm talking about illumination wires I should ask you...did you even hook any of those up?  Most aftermarket head units don't even have dimmer and illumination wires and usually we just end up taping off each one of the factory wires individually and not even hooking up to them.  If incorrect connections are made to these wires it can sometimes damage the vehicle so usually we don't take the risk, and unless you really really want to use your head unit's dimmer function, it's just not worth it for you to do it either.

You said it will stay turned on for about 5 seconds but then turn itself off.....will it come on again once you turn off the car and then turn it back on again?  Or does it stay dead indefinitely?  If it stays dead it could be a blown fuse. 

Also try to see if it comes back on at the same radio station that you had it on before it turned itself off.  If it resets to the default 87.9 or whatever it is, then you have a problem with your +12 volts constant wire.

I'm still  trying to think of some other possible ideas for you to try.......

Doing the 3-wire hookup serves other purposes besides helping to tell you whether or not it's the deck that's bad.  It lets you isolate the spot of the problem in terms of the wiring.  In other words, if you only have those 3 wires hooked up and everything works, then you tell yourself, "ok it's either something with the speaker wiring or the illumination wires or the power antenna wire".  Then you add on a wire one a time (or for the speakers wires, one pair at a time) and test the deck again to see if it works.  Keep on doing that until you've determined which wire is the one at fault.

I also forgot to ask you if the vehicle had any kind of premium sound system in it, like the jbl system?  It would say either on the sail panel speaker grilles or on the factory unit itself, if that were the case.  I'm assuming it's just the standard stock system but wanted to make sure....

Finally, even the best of us forget the simplest things every now and then, and with that being said I'll ask you.....did you remember that you have to press the source button to turn it on the first time it's hooked up?  The display will either stay blank or just the clock will be displayed, until that source button is pressed.

Happy to help, and even more happy to hear that the solution was so simple!