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79 Wiring Problems

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Old 08-09-2007, 11:07 PM   #1
galloway
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Default 79 Wiring Problems

Hi, all! First I'd like to say that looking through this site I've found many helpful things, and everyone seems so helpful! This is my first post, and hopefully someone can help with my problem.

My mother purchased a 1979 Corvette just last month, and I had offered to put in a radio for her. After much struggling with the dash speakers, I was finally ready to hook everything up and test it out, but it turns out we have a problem... I'm not getting any voltage from the battery wire, nor the ACC wire. (I could be wrong on the colors, though. There's blue, yellow, and grey, and I'm getting voltage from blue?)

So here I am, hoping that the issue is related to a fuse, and as I start to look at the fuse box, I notice there are two sets of wires that are just not connected!



I'm not certain if you can tell by the picture, but the harness has 3 wires running to it: red, white, and brown w/ stripe. The other (top right) has blue and orange.

I've looked around on the inside and I can't seem to find anywhere these would go, and any help would be appreciated.

And before I forget, is there anyone here that knows where to find the diagram for the fuses? Half of them are smudged and impossible to see. Thanks in advance!
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Old 08-09-2007, 11:28 PM   #2
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To be honest you're making this a lot harder than it needs to be. The stock harness, to me, did a **** poor job of supplying the radio with solid power and ground.

If I were going to re-do a stock stereo I would run all my own wires. The radio needs a constant, an ACC, and a ground.

The pink wire in the harness should be constant 12V. The yellow is the IGN circuit, and black is almost always ground. I would even run my won ground from the birdcage.

Test and check the above, and then just run your own wires to the speakers from the radio, or continue to test the factory wires for current using a 9V battery or a good multi-meter.
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Old 08-10-2007, 12:35 AM   #3
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Quote:
Originally Posted by Durango_boy View Post
To be honest you're making this a lot harder than it needs to be. The stock harness, to me, did a **** poor job of supplying the radio with solid power and ground.

If I were going to re-do a stock stereo I would run all my own wires. The radio needs a constant, an ACC, and a ground.

The pink wire in the harness should be constant 12V. The yellow is the IGN circuit, and black is almost always ground. I would even run my won ground from the birdcage.

Test and check the above, and then just run your own wires to the speakers from the radio, or continue to test the factory wires for current using a 9V battery or a good multi-meter.
Thanks for the reply! Your advice is appreciated. The problem is she wants an aftermarket stereo put in, and the radio requires exactly what you said above (plus a circuit to the dimmer). I have a yellow wire (no voltage) a grey wire (no voltage) a blue wire (12v constant) and a black (verified as ground). There seems to be no pink wire, and everything looked stock, minus the blue wire was jumped to another yellow in the stock harness for some reason.

I'm still worried about these loose harnesses near the fusebox, however, because they may have something to do with either the voltage going to the radio, or the reason the AC fan doesn't work (a completely different issue that I'm not worried about right now). I'm hoping someone will be able to point out what these are and which fuse is to the radio, and maybe with some luck everything will work out.

Thanks again!
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Old 08-10-2007, 01:05 AM   #4
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The connector for the stock radio should have a yellow wire that is +12 volts switched on with the ignition, a grey wire for the illumination and a black ground wire. The red, white and brown connector looks to be for cruise control switch on the blinker stalk if you have cruise. I can't seem to find a blue and orange connector combination on my wiring diagram but will look again and post what it is for if I find it. What the stock radio doesn't have that you need for most after market radios is a constant +12 v supply wire.
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Old 08-10-2007, 07:19 AM   #5
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Yeah the pink was never used for the original radio harness. It'll be buried in the large bundle that wraps up and around the driver's gauges.

There will also be a spare ACC line in the fuse box that you can tap for your 12V switched, and that completes the main three.

As far as the illumination wire it would normally go intersect with the headlight switch. Personally I hate when radio face plates dim and brighten with the lights so I either don't use the function or have it operate switched by the IGN or ACC circuit. That way the face plate lights are always on.

I've installed several C3 stereo systems and found running your own wires to be better than using stock in many cases. This goes for the wires to the speakers and sometimes even the hot and switched wires.
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