1985 Stereo
 

We are trying to installa Sony GT-130 stereo in to my son's 1985 RX7. There is no kit for the car and Best buy says we have to hard wire it in. I see three harnesses, but dk which is for what. I have a list of in-car wires from an installer website, but they do not correspond to the car. Mainly, I cannot find a hot power wire. Any advice out there?

Three power related plugs behind stock stereo for 84-85.

J-03 has three terminals. Red/green is dash lights, Blue/green is from J-02-power antenna relay, Blue is from J-04.

J-04 has 6 terminals. Only 4 have wires. Blue goes to plug J-03, Blue/white is 12v when key is in ACC position, Red/green is dash lights, Blue/yellow is 12v at all times. In some stock installations there is a jumper wire between the Blue/white and Blue wires in J-04.

J-05 is single wire plug. Blue/yellow that has 12v at all times.

You can download the wiring diagrams and Factory service manuals here.
http://wright-here.net/cars/rx7/manuals.html
http://foxed.ca/foxed/index.php?page=rx7manual

Confused
 

Where are the speaker wires then? THis is my first Mazda radio install. On my domestic cars all I would do is hook up the 12v to key and my speakers and I would be done.

The only blue-white wires are those grouped with what the 12volt.com website says are speakerwires. Nothing corresponds to what I was told here or in the manual I downloaded from the link referred to on this post.

To find power use a test light or a voltmeter:
-acc power (key on)
-constant power (key off) for memory

To find speaker wires, use a 9 volts battery and proceed to connect 2 wires at a time to the battery. When you match two wires for a given speaker, you will hear static from that speaker.

You have an SE? There are two amplifiers under each storage box. You can find your speakers wires there.

This can get a bit tricky. There were several stereo options available in 1985. Manual tune radio, electronic tune radio(ETR), cassette player, graphic equalizer, speakers powered by radio, one amp or two amps. You have to determine which one was original in the car. For example I have a 1985 GS but it has an upgraded stereo system. Remember that the dealers also installed dealer options. That said if you go to the 1st gen. FAQ thread there is a question about finding manuals. In that thread there is a link to electrical diagrams. This may help you.

Good luck!

If none of the wires match the FSM someone must have done some customizing.
Front speaker wires are in plug J-10. Four terminals. Blue/red and Blue/yellow are right. Blue white and Blue/green are left. It connects the speaker terminals from the front amp, under the right side storage bin, through the center console, to the front speaker harness. You can unplug the plugs and plug front leads from stereo into the plug with the male spade terminals to connect to the stock front speaker wires. Front and rear signals go from head unit to amps through heavy multi-pin cable by way of the joy stick in the center console. You'll probably want to run wires under the center console and into the left storage bin for rear speakers. There is a 4 terminal plug there, next to the rear amp, where you can connect to the stock rear speaker wires.

I have to go out to the car tomorrow. Wire colors do not quite match comments here or FSM. For instance, the plug which has three wires has two solid blue and one red/green. I cannot tell which radio the car had as it had no radio when we bought it. I don't think it had an equalizer because the only hole open was for the radio. The little cup compartment was in the second hole abouve the little door. It is just a base model car.

If you have downloaded the FSM, check the audio system diagrams and wiring in Chapter 15, Body Electrical.

I'd just run new speaker wire and do away with the amps. they don't work unless you have the stock stereo anyway. then all you need to find is a 12V constant, and 12V switched, and run new speaker wire (witch is better than the stock speaker wire anyway). thats just my 2 cents.