I just installed an aftermarket HU in my 95 Avalon XLS, factory 7-speaker w/amp. I ran into some issues I have not seen addressed in any of these write-ups, and I wanted to share my solutions and observations.
First, thank you thank you to slickwilly, swiftjustice, and everyone else who has contributed to these threads. The info was invaluable!
So here's what happened:
I have a JVC KD-HDR50. I had previously installed it in a 96 Hyundai Elantra Wagon, using a Metra harness adapter, easy install, easy removal when I traded up from the wagon to my Avalon. No problem.
I read everything I could find online about stereo swaps in these cars. Very, very helpful, and I was then braced for shinanigans.
My JVC HU has 4 RCA outputs, so I figured I could use them to get an un-powered signal to the factory amp. I'm too cheap to pay 15.00 for a harness when I have big piles of RCA cable in my closets, so I decided to splice everything by hand.
Here is a link to Crutchfield's information on this car:
The three connectors on that page aren't clearly labeled. The white one they show at the top is the connector at the back of the factory head unit, most of it's wires lead to the amp. The two lower connectors are plugged into the amp, behind the glove box. The one on the left is the output from the amp to the speakers. The one on the right is the input from the stereo HU to the amp. In my car they were blue and green, respectively, but I understand they can be different colors.
So, I connected my JVC's power and such by cutting the wires at the factory stereo connector in the center of the dash and twisting in.
One small note there: you will notice that the factory connector has 2 pins for lighting the HU. Pin 2, "Illumination", and Pin 9, "Dimmer". The First time through I connected Pin 2 to the orange "Illumination" wire in my JVC unit. When I turned it on, all of the display was lit up like christmas, with every symbol lit. Too much power. Second time through, I connected to Pin 9. Now the display behaves the way it should, and responds to the dashboard dimmer circuit when the car's running lights or headlights are on.
I had read about making sure to connect to the amp's remote-on lead, which is Pin 1 at the connector. My new HU has a blue wire just for that. I understand thay they pretty much all do. Sweet.
Then comes the first snag. What to do with the RCA shielding? I have some experience with installing shielded wiring for VOR and radar receivers, but I wasn't totally sure that this was the same thing, so for the time being, I simply connected the center signal pins of my RCAs to the 4 Positive leads going to the amp, Pins 6, 7, 14, and 15. I twisted up the shields and taped them back to the insulation to keep them out of the way. Some of you already know what happened next.
When I got everything hooked up and reconnected the battery, the stereo powered on and I had sound - at the front speakers only. As I mentioned, the display was on fire, so I knew I had guessed wrong about the illumination power. I turned on the car's headlights to see if that would affect the display, and I got a loud, clear, evil hum from the front speakers. Ya. Shielding has to go somewhere. I had a very strong suspicion that that's what Pin 12, "Signal Ground", was for. But I wasn't totally certain whether the RCA shielding should go there, or should ground to chassy. So I read more. Here are some awesome articles about audio grounding:
and this thread was helpfull too:
If you look around on the net, there is a whopping metric ton of info on the subject. Back to our Avalon.
Turns out Toyota was just way ahead of the curve back in 95. They used an isolated signal ground in their factory radio, which gives you very clear sound, free from interference and EF noise. But in order for it to work, it has to be connected to the chassy ground *internally* at either end of the chain - in this case, at the stereo HU and at the amp. Fortunatly, this is how all RCA connectors are wired in aftermarket stereos. So I determined that by simply connecting the shielding of all 4 RCA leads to Pin 12, "Signal Ground", I would eliminate all of the noise and interference. Cool.
Before doing that, I decided to make sure everything else was working properly, so I ran the JVC through it's paces. I used all of the input options, radio, cd, ipod, played with the fade and the eq, and quickly found snag #2.
The front speakers sounded great. The rear door speakers sounded muddy and quiet. I couldn't hear the subwoofer at all. Nuts. Being somewhat familiar with the internals of my JVC unit, I got into the menus and played with the settings. I found that by switching it's internal crossover to pass as broad a range of frequencies as possible to the sub, and then turning the subwoofer gain all the way up, and then fading everything way toward the back, I could get sound out of the sub. But the rear door speakers still didn't sound like they were doing much, and the overall sound in the car was very, very quiet in the lower mid-range frequencies. Curiouser and curiouser. But I had kind of thought something like this might happen.
The RCA outputs on the HU are not labeled left and right, front and rear. They're labeled left and right, Front and Subwoofer. JVC had assumed that most people would use the powered speaker outputs from the HU's pin connector to drive their car's front and rear door and deck speakers, and optionally, maybe decide to connect a subwoofer, and an accompanying amp, to the RCA subwoofer output. Therefore, they had the sub-out filtered to the appropriate frequencies. The filter is adjustable to three levels, as I mentioned. But it just doesn't go up as high as the rear speaker outputs.
So my dilemma became this: If I used the un-powered RCA outs to the factory amp to the speakers, I had poor sound, but I had the subwoofer. If I used the powered outputs, I'd have to bypass the amp, straight to the speakers, I'd have full range of frequencies, but no subwoofer, unless I bought a subwoofer amp. (This is what sickwilly did in his car.)
Some of you may be asking, "But why not just go into the JVC's menu, and use the Internal Amp Switch to make the speaker outputs un-powered? Then you could connect to the factory amp, which would give you the full range of signal, and let the amp drive all 7 speakers. Just like the factory stereo did."
I thought about that. But then I remembered that the speaker outs from the JVC are 2-wire. One positive and one negative for each speaker. The inputs for the amplifier are only one positive for each speaker, and a common Signal Ground to provide reference and grounding for the whole thing. I called a few installers, and no one knew of a way to connect those two things together. Nuts. Again.
I didn't want to buy a sub amp. The whole point of this project was to spend as little cash as possible.
Then, while I was on the phone with BestBuy's stereo installation team manager, who kept saying helpful things like, "Wow, that's messed up. I dunno, man." it hit me. I already had a subwoofer amp. Toyota had put one in the car, right behind the glovebox. Duh. Duh. Duh.
So this was my solution: I used the powered outputs from the JVC's connector, bypassing the amp, straight to the speakers. Wiring them into the amplifier output wires under the glovebox was joyfull, only the opposite of that. By the way: you don't have to do that work *through* the glovebox opening. Once you unplug the connectors from the amp, you should have enough harness to gently pull them down, so that they're hanging out *under* the dash. This gave me a bit more room to work. The resulting bundle of 8 wires going from the area of the amp to the area of the stereo tucks very nicely into the trim rail that forms the bottom of the glove box opening.
Then, I wired the RCA Subwoofer outputs from the JVC to the factory amplifier input, at the factory stereo's connector, like this:
Sub-Out Left : center wire to Pin 14
Sub-Out Right: center wire to Pin 15
The shielding for the RCA cables, I twisted together, and ran *both* of them to Pin 12, Signal Ground.
Another note on grounding: Because of the way Toyota wired this equipment (ahead of their time, remember?) it is very highly advisable to be sure that, if you are going to used the factory amplifier at all, Pin 11 on the stereo connector should be tied to a chassy ground somewhere. In the original stereo, this went to the unit's frame internally, I think. In my application, I teed the wire from Pin 11 to the Chassy Ground wire coming out of my JVC, and bolted them both down to the dashboard bar. If you look forward through the hole where your stereo used to be, you'll see a steel tube, about 1-1/2" diameter, running from left to right behind the dash. A few inches toward the passenger side from center of the car, there is a grounding point with a very convenient 10mm nut. I'll try to get a picture of it when I pull the stereo to install the dash pocket later.
So. After all that, everything connected, screwed back down, and the dash re-assembled, the stereo sounds great! I still have the subwoofer settings in the HU cranked all the way up - the front door speakers are a bit overpowering, and I have it faded back a little bit, maybe 3 or 4 out of 10. The little 8" sub hits pretty good, and all of the door speakers sound remarkable good for their age. (Anyone know who made them? I've heard that some of Toyota's speakers are JBL, but I don't know if that applies to these older Avalons.)
You might have noticed that I didn't say anything about connecting power for the powered antenna. That's because mine was broken when I bought the car. Motor works, mast is snapped off and corroded into a permenantly retracted position. I replaced the whole thing with a 7-dollar 31" one-peice Metra whip from Autozone. 10-min install, and I think I can get radio from Japan on the thing. Toyota used industry standard connectors for their antenna lead from the stereo to the trunk, so no adapter was needed to plug in the new antenna. Many, many blessings on them!
I think that's about it. This post got a lot longer than I intended, but I hope it's usefull. I'll edit in some pics when I get a chance, but I was on limited time when I did the job, so I didn't get any shots of the process, or my ugly, ugly wiring job.
Now I'm off to find out where the power steering fluid is leaking from. Yay!
I just remembered (right after posting of course) that I wanted to say something about the Metra harness that is available. You know, the one with the 4 RCA leads, that plugs into the stereo connector in the center of the dash.
I haven't held one of these in my hand, so take this for what it is - conclusions logically deduced from research and observation.
I've read several people talk about using this harness to "bypass the factory amp", or say that it will "bypass the subwoofer portion of the factory amp." It seems to me that neither of those things are likely to be true. Here's my reasoning.
The Metra harness connects to an aftermarket head unit, and to the car's stereo harness, which is where the factory stereo plugs into the factory amplifier. Therefore, it is not bypassing the amp. It uses the RCA outputs to send an un-powered signal with a common signal reference (signal ground) to the amplifier. The amp powers the speakers. Which brings me to the second point.
The factory amp only receives 4 signals: front left and right, rear left and right. It then amplifies and splits the signals to 5 ouputs: front left and right, rear left and right, and subwoofer. (I'm pretty sure the 1" front door tweeters are jumped off of the front door speakers. Baseless assumption on my part.) So, if the Metra harness is sending the signal to the factory amp, the amp will power the subwoofer. If the subwoofer sounds very weak or quiet, I think it would be because the head unit's "rear speaker" rca output isn't pushing frequencies low enough and hard enough to really push the sub. If the head unit has 3 pairs of rca's, front, rear, and sub, this would be a very safe assumption.
Just throwing in an extra .02!