Okay, so I just recently bought an 1989 Iroc Z. I love the thing, but that's not the concern right now. When I bought it, it had a newer Pontiac Stereo with auto reversing and all that fun jazz. I bought multiple Cassette adapters because I thought they would be a cheap way to play my music and such. Alas none worked. So I bought a new stereo. As I go to pull out the Cassette Stereo I notice that it is not the original harness. I think nothing of it. I cut the wires and attach them to their designated spots on the new harness.
I started with the ground and hooked it up to the original wire, I wanted to go to power next. Of course, they say "The orange wire should go to the red wire" I was like, simple enough. Alas, I don't have any plain ORANGE wire I have an orange wire with a black stripe. I thought nothing of it. I kept on moving down the old harness cutting wires. Hooking up what I think was the accessory yellow to the designated spot on the new harness. Going through the speakers was a breeze then the new harness was all filled up. But, whats this, one wire left on the old harness. It is yellow. But that's impossible, no diagram says there are 3 yellow wires.


TL;DR
( So. I know this was a lot to read, but I have no power to my stereo in short, and I have no idea what to do.)

 

Here a wiring diagram for the factory radio. You can use it to wire your new radio. You wouldnt by chance have the bose system in this car? Bose system shows an orange wire in it.

 

If only it was that easy. I used a wiring diagram in the first place. The orange wire doesn't exist. I have an orange wire with a black stripe.

 

You might have factory bose in your car. Here is a diagram for the bose system. It has an orange wire in it.

 

So the Orange Black stripes is also a power source. Good to know. But if that is the case, why doesn't the Stereo have power? If this is right, everything I connected should be correct.

 

Fuse might be blown for the orange/black wire. Its a constant 12v wire and should have power all the time. That fuse is located in the aux. fuse box under the dash to the right side of the steering column. Push in the tabs and it should swing down to gain access to the fuses in there.

 

Alright, I will look at that tomorrow afternoon. Thank you my man, I will get back here with results.

 

I know this sucks. I had the same problem. I will work on and figure out a mechanical problem all day long, but when it comes to electrical problems, I get frustrated very easily and give them the proverbial finger. For Christmas my parents payed for a new radio install, speakers, amplifier, etc. Solved my problems. Best of luck.

 

*sniff, sniff* a redditer.

 

Pardon?

 

So I figured out the problem. While looking at the fuses I found the Orange wire. Clearly tampered with. Spliced with it was the mysterious 3rd yellow wire. I looked at the old harness under the tape, the orange and black stripes was connected with the third yellow and then connected to the harness. SO, I simply repeated that, and problem solved

Thanks all!