I have just put in a new radio in the process of wiring the radio I seem to have caused the top four fuse banks of the fuse box to drop there voltage to only 10-10.5 volts the bottom 3 seem to have the normal 12 volts. Now my wipers wont work and the turn signals have stopped also. But the lighter,interior lights and gauges work. I have unpluged the new radio and every thing started to work again then the same items have stopped working again. Any thoughts on the cause?

I would put all the wiring back the way it was and work foward again slowly.
I would even remove the radio until the other items worked again.

Sounds like something is dragging those circuits down.

good luck..

I have removed the radio but no luck. The wiper seemed to start to work again if I used the lighter socket. I was wondering if there is a common ground or the wiring harness has a common power source for these circuits?

Sounds like you are creating an indirect short through the radio, are you sure you are connecting it correctly?

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Geezer

I thought of that so I unhooked the radio but every thing stayed dead. If I try the right combination of accesories like the lighter or lights things would start to work again. But now the turn signals have died and the fuse panel is not getting the full voltage to the fuses. This is without the radio hooked up. as always any comments would be appreciated. Thanks

A couple of things that come to mind...make sure you're not grounding any of the speaker wires. I'm not sure if the factory speaker wiring did this or not, but be certain. Modern amplifiers excite both the hot and the ground wire for the speakers out of phase, so grounding any of the wires will result in a short circuit.

Secondly, make sure you don't have a bad connection at the fuse block or else where. It's not uncommon for fuse terminals and other connections to corrode. They'll show 12V under no load and drop dramatically when a load is applied. Use a voltmeter to measure accross connections. Test the power wire to fuse terminal, fuse terminal to fuse, fuse to the other fuse terminal, fuse terminal to wire etc. Find out where your other 2 volts are going and you've found the problem. Do the same on the ground circuit. Also a missing or damanged ground strap or other ground connection can make it look like you're power circuit dropped 2 volts when in fact the ground circuit is rising 2 volts. Measure from battery ground terminal to frame, frame to chassis, chassis to your gound point etc. Any voltage drop that approaches 1 volt is suspect. Bad connections can also result in fires. Check the fusable links also. Look for charring. The fusable can remain in tact, but still present a high resistance to a circuit due to corrosion or a previous high circuit load. A test lamp in series with the circuit can also be used to trace high current shorts.

-dnult

Look at dnult's suggestion. With your meter lead scratch into the fuse clips. Then measure the ends of the fuses. Guessing that oxidation of the clips and fuses may be the problem. A quick, no cost test. If you see the drop across the fuses, clean the clips and replace the fuses.