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NYTEPSYCE
09-03-2010, 07:37 AM
HAVE A 1990 CELICA GTS WITH A SYSTEM 10 STEREO THAT I AM CONSIDERING UPGRADING TO AN AFTERMARKET HEAD UNIT. ONLY PROBLEM IS THE STICKY FOR THE METRA HARNESS STATES IT WON'T WORK WITH A 1990 SYSTEM 10 DUE TO THE DOUBLE CONNECTOR INSTEAD OF A SINGLE CONNECTOR LIKE LATER MODEL (1992 AND UP) SYSTEM 10 STEREOS. ADVICE ANYONE?
:confused:

delivery boy
09-03-2010, 09:56 AM
Hey there. I think I've read everything there is to read about this. I have a 91 gts and had to same problem. I think theres a ton of threads covering this but yea. There is a connector that comes off the stock deck and another harness with the double connectors a little further back. If you use the double connector you will bypass the stock amp and not get anything from the door speakers. The 92 and 93 had a 15 pin single connector harness that came off the stock deck that could use the stock amp. The 90 and 91 had a 14 pin connector that came off the deck so you cant use the 92 93 metra harness. As far as i know you can use a wire harness made for the mr2 and keep the stock amp.

http://www.dynamicsounds.co.uk/autoleads-pc9406-toyota-wiring-harness-adaptor-lead-p-9212.html

http://stephenmason.com/cars/mr2pc9406.html

I emailed the company that makes them to see if it would work with my celica and they told me:
Hi,

The MR2 audio system was fitted to some Celica’s so the PC9-406 should be fine.

Regards

I didnt end up getting it because I can find a used 2 channel amp for less money then what the harness would cost. The company is out of england and its a little pricey with shipping.
So you have 4 options:
1. use the double connector harness and bypass the stock amp and go without the door speakers.
2. use the double connector harness and install a aftermarket amp and run the door speakers off of that.
3. get the mr2 harness.
4. cut wires and hook up your deck that way. ( I cant tell you about that)
hope this helps. I dont know much about car audio but i think ive read everything on this site about system 10.

TBayToyotaBoy
09-03-2010, 03:23 PM
Well, luckily for you I can help with option #4 that Delivery Boy mentioned. I went through a long and painful process getting my stupid stock wiring harness (1991 GT-S) to work with my new aftermarket single-din head unit.

http://www.celicatech.com/forums/showthread.php?t=45595

It's a long thread, but I posted all of my steps in there. The trickiest was wiring the RCAs to the wiring harness so the stock amp would get unboosted signal--otherwise I was going to blow all of my speakers above volume level 3 or 4.

Good luck!

--Tim

NYTEPSYCE
09-08-2010, 06:58 AM
Tim,
Thanks for the help. When i get my car back from the body shop i'll pull the system 10 unit and follow your instructions. Do i really need the secondary aftermarket amp hooked up as well? (the unit i bought only has one set of rca plugs).

TBayToyotaBoy
09-09-2010, 02:50 PM
Well, are you going to be running subs? Because I would think a separate amp for the subs is essential. Splicing-in to run both the 10-speakers and the subs all from the stock amp would be tricky and probably wouldn't sound as good as it could with a dedicated sub amp.

On the other hand, if you were to use the one pre-out you have, splice it to a) the four positive leads (front left/right and rear left/right), and to
b) the RCA wire leading to your sub amp.

I'm not sure how well that would work, but it's unamplified signal coming out of the pre-out, so you shouldn't lose signal strength...I think.

Anyone know better?

P.S.: NYTEPSYCE I have copied the relevant wiring info from my post so you don't have to scroll through the entire thread:

"Well, after three tries I have the head and subs in and the System 10 sounds better than anyone else's set-up I know. My friends have spent huge dollah bills to get the same quality sound that these 20-year-old systems are still capable of. I've never had such a sh!t-eating grin on my face before, especially when the guys heard it and realized it was almost entirely stock.

To eliminate the hiss at low volume, I spliced both the fronts and the rears to an RCA and used the front pre-out for all ten stock speakers and subs. My deck only has one rear pre-out, so the subs took that up. On the 1990-91 System 10, you have to solder all four of the negative speaker wires to the white signal ground in the harness (SGND). I spliced my amp remote wire into the pink/blue stripe wire in the dash, so both subs are controlled properly.

I eliminated the following unnecessary wires from the stock harness: red "BEEP" wire; green and green+white stripe illumination wires; brown "MUTE" wire; black/red stripe antenna wire. My deck has an antenna amplifier built-in, so I get all the stations without the powered antenna hooked-up."

NYTEPSYCE
05-20-2011, 06:18 AM
I bought the mr2 harness that was mentioned in this post and will be able to connect the front and rear speakers to the aftermarket deck. However i only have one harness leading into the factory deck with a cable (about the size of a rca looking like a smaller version of the antenna cable hook up) connecting into a hole above the antenna cable. It has something to do with the sub amp because it was disconnected and I was having issues with the sound quality before i found out it was unattached and after I plugged it in the sound quality was 100 % better. All the speakers had sound coming through, even the bass speakers on the doors, but it used to fade in and out before I reconnected the cable. My question is, with the aftermarket deck, were do I plug in the cable and does this eliminate the need to separately wire the door bass speakers? I don't see the wires for the door bass speakers and they are not part of the single harness. (my aftermarket deck has two rca pre outs on the back as well as a sub woofer rca cable).
Nytepsyce