Audio Systems: AVALON UPGRADE, light fuse, wire taps

Question
I INSTALLED A PIONEER HEAD UNIT INTO MY BUDDY'S 95 TOYOTA AVALON, THE UNIT WORKS FINE, ALL SPEAKERS WORK. THE ONLY PROBLEM IS THAT THE PANEL LIGHT FUSE WHICH CONTROLS THE DASH LIGHTS, KEEPS BLOWING WHEN YOU TURN THE LIGHTS ON. MY GUEST IS THAT I NEED TO TOTALLY DISCONNECT AND DISABLE THE POWER TO THE FACTORY AMPLIFIER. ISTALLION METHOD USED WIRE TAPS ON ORIGINAL HARNESS FOR HOT,ACC, AND GROUND. WIRE TAPS AT THE HARNESS ON THE FLOOR BOARD WHERE THE SPEAKER WIRE ARE HOUSED. GREATLY APPRECIATE YOUR EXPERTISE IN ADVANCE.

SEAN.

Answer
Seems to me the circuit is overloaded.  Some how you have switched wires such that the headlights are drawing current from the dash/instrument panel.

Have you tried a slightly larger fuse?  If it is a 20 amp,try a 25 amp.  Doing so will tell you if it is just a case of drawing a little too much current or if there is  a short some where that blows any fuse you put in.  Think of it as  a diagnostic method.

You may have to run the circuit that is overloading the panel lights on a separate line back to the cars 12v system.  Nothing wrong with fishing another wire through the firewall and off to the battery or to a switched line off the big fuse box near the battery.  

You can easily tell what line is causing the overload situation by disconnecting the Pioneer head unit; check for fuse blow, then connect one wire at a time, etc.

Speaker wires should not be involved in this unless you think they have been pinched or insulation scraped off and causing short outs somehow.  You can check it with and ohmmeter to ground.

Wishing you the best,
Cleggsan