I just pulled the radio(weather coroperating) and what a sight! The moron who put this radio in cut the factory plug out and spliced the wire.What a mess,I guess he didn't know he could get an adapter to make his connnections.Now my problem the manual I have only shows power,and speaker wire colors.Aa in it shows four wires coming off the radio.In reality there are a mess of wires spliced ,and I wondering dose anyone have a detail wiring diagram for a 75.The radio has a diagram on it,but I need to know what I hooking to.I had to take a brake just looking at that mess makes me mad .There are wires going to other things from the radio.I have the base corvette for 75 so it should only have the base wiring.It may have wiring for stero,but not knowing what gose where I am at a lost

Hi Rick,

I think BUBBA has been in all of these cars at one time or another.  I had similar problems with the stereo wiring in mine when I got it so you aren't alone.  That being said, I cant help with the 75 wiring but I do understand what you are feeling.

Yes Joe it's an aftermarket radio.The radio has a diagram for the wires on it ,that said I'm not sure that they are hooked up right.In my car there are only two speakers up on the dash,I disconnected them today ,they were shot.I put two speakers in the back  for now.

             Rick

Hey Rick, A bad speaker in the system can cause the amp in a radio to overheat and make the audio fade out. If you reply with a list of the colors of the wires out of the radio, I may be able to identify them. Is there a brand name or model # on it?

Unless someone made some after market changes to the wiring, the color codes should be:

Yellow - hot when the key is in the on or acc position

 Ok here it goes coming from the radio:red to orange(looks like aftermarket noise filter)then red to yellow. Blk to Blk (noise filter)Blk to Blk. Then there is red to orange.And lastly coming off the radio and going to the fuse box is a brown wire with inline fuse.Emil I saw the yellow wire and black wire ,but not a gray one.The next time I pull everything apart I am going to do reconnections and I look for the gray wire. Thanks Guys.

Hey Rick, The next time you have the wiring exposed, I suggest taking the noise filter out of the circuit. The filter may be the cause of the power fading out. If the radio is OK and the electical system is in good shape, it shouldn't need a noise filter.

The gray wire is for internal lighting of the radio from the dash light circuit  If someone installed an aftermarket radio it would need one hot wire switched from ign(hot with key on), and a power wire hot all the time to keep the memory of the radio presets and clock. the brown wire may have been run by previous owner for hot all the time if you pm me email address I can send radio diagram circuit for 1977 or 1980 which will show factory wiresrraider12010-10-09 17:16:36