How to use the OEM amp Wiring
 

Hi all.

Havent seen a thread like this yet so I thought I'd post my findings. This project is far from complete and I havent even decided how I'm going to finish it off. Might go with micro amp and small sub or go all out with 2 full size amps and larger sub.

I digress - here is the meat and potatoes of the thread:

The oem amp harness uses a standard toyota HU harness (ie Metra 70-1761) however, the wires are far from standard so I took some time, repinned the harness and am now trying to decide how to use it.

Pics:
The newly repinned harness
Attachment 45328

For those that dont know how to remove the pins simply take a large sewing needle and lift the little white plastic tab while pulling out the wire. Fair warning: some of those buggers are snug, I had to use 2 hands on the harness and my teeth to pull the wire out.
Attachment 45127
Attachment 45128

Im hoping to maybe use http://www.crutchfield.com/p_020XC14....html?tp=35782 to minimize space. This wiring trick will only amplify the door speakers though. Not the dash or rears.

PIN Map:
Attachment 45329
Attachment 45330

Wire colours:
Red = Battery + (always on) [PIN 1]
Black = Ground [PIN 2]

White = LF Speaker amplified out (black line means -) [PIN 1 and 5]
Grey = RF Speaker amplified out (black line means -) [ PIN 2 and 6]
Blue = remote turn on [PIN 8]
Green = Left speaker signal input from HU [PIN 3 and 9]
Purple = Right Speaker signal in from HU [PIN 4 and 10]

*** Fixed first post pin picture, all correct now ***

Also for the skeptics - a little proof that this will fit:
Attachment 45129

I guess I'm not entirely sure what this accomplishes.

Do you have any references that you used to determine the correct pins?

what are you trying to do ?

Well using that wiring you can attach a micro amp that will push 50w to the door speakers and leave 100w bridged for a sub all using stock wiring.
http://www.crutchfield.com/p_500KTP4....html?tp=35782
http://www.crutchfield.com/p_020XC14....html?tp=35782

Or if you just want to retain stock speaker wiring you can run a power cable and RCAs while attaching a full size amp. Plus you now have access to high level inputs if you dont want to run RCAs and a remote turn on cable. All without cutting and splicing.

I used the BRZ wiring manual found here: http://www.ft86club.com/forums/showt...ht=shop+manual

What this does is use the stock wiring to bypass and replace the rear amp with something aftermarket to get some real power to the door speakers.

I'm looking to do almost exactly the same thing, but I was under the impression the harness provided everything you need including power and signal. Why couldn't you run a real amp instead of a mini-amp?

Nothing major just a small 4ch bridge to 2ch to put some power to the door speakers.

Do you know if the signal from the HU (green and purple) pre-out level or high level?

Well according to the wiring diagram (at least as I interpret it) they are high level inputs. They come from the HU, pass through a junction connector in the dash (where they are spliced into the dash speakers) then to the amp in the back.

That'll still work.

So if i wanted an aftermarket amp back there then I'd do Green/Purple into high level inputs on amp and then White/Grey to the powered output of the amp?

Then red/black/blue for power & remote?

That is correct :thumbup:

Im getting a used Alpine MRP F240 tomorrow from a friend for $0. That amp will require some beefier wiring though so ill be running a power wire, and prolly RCA's in the process...

**EDIT** Just ran the numbers. Amp uses a 15A fuse (label ANP) so a 200 watt amp would be just fine on this circuit. HU uses a separate 7.5A fuse.

What would happen if you used something like that with the little power wire out of the stock harness? 40w x 4 doesn't seem like all that much...

Makes me wish the battery was in the trunk.

Well it could probably be done with a Class D amp. But the Alpine MRP-F240 is an AB amp which is less efficient but is also said to have more rich and accurate sound. That being said I would just feel better personally having at least 8ga wire running back there for power and ground on that one. The Micro amps are class D and have less power requirements/more efficiency than AB or A.

Keep in mind the stock amp is probably pushing around 25w RMS with less advanced crossovers (if any). 40w RMS is an appreciable upgrade as far as power goes.

Edit** I think the Alpine manual recommends 10 gauge wire which means 10 is more than what is required (they wouldn't low ball it)

Ok good to know. I'm not willing to run a power wire, but I don't want to melt the stock harness by trying to pull too much power.

Looks like I'm going to need to find something class D, and those mini-amps look like they'd do the trick, 90watts RMS when bridged to 2ch is definitely good enough for what I'm trying to do.

If I wasnt on such a tight budget with home renovations I'd be grabbing one of those for sure! I just added some pics on first post of a pin map. Should help you out!

I am going to do this using an Alpine KTP-445U which is a Class D mini amp. I'll post a review when it's complete. Thanks for the write up, I've been looking for a non-wire hacking solution.

Awesome

So If I was planning on adding a single sub and amp in the trunk I could use that harness to power it all without needing to run any power, ground or remote?

I would run the RCA from the back the the head unit and that would be it, right? I guess if I wanted to I could also get a amp and give more power to the door speakers, right?

Any Idea on if it is possible to make the door speakers full range and not sub, since I would have a sub in the rear???

Power wire is not big enough to power a subwoofer amp. Unless you get a very small wattage amp that's class D

BRZ Amp install without cutting, splicing, or otherwise hacking into factory wires
 

BRZ Amp install without cutting, splicing, or otherwise hacking into any factory wires:

Today I installed an Alpine KTP-445U 45x4 RMS amplifier in place of the OEM amplifier. This amp is designed to go behind a factory or aftermarket stereo to provide more power to the speakers. The Alpine works on a 15A circuit which is (conveniently) identical to the OEM amplifier. The OEM amplifier runs only the 2 door speakers and I wanted to retain this setup to only power my Infinity Kappa 62.11s in the doors. The OEM HU provides plenty of power for the Reference 3.5s in the dash.

The OEM amplifier connectors are the same connectors used in 1987 and up Toyotas. (credit: RandomHero on FT86Club.com http://www.ft86club.com/forums/showthread.php?t=42239) So, in order to install this amplifier without cutting any wires, the only item needed is the Metra 70-1761 Radio Wiring Harness.

Here is the amp and Metra harness out of their packaging:
http://farm8.staticflickr.com/7356/9...e2fcecc78c.jpg
IMG_4169 by zdr93523, on Flickr

Then, following the advice of RandomHero on FT86Club.com http://www.ft86club.com/forums/showthread.php?t=42239 I removed the pins from the Metra harness and repinned the connectors to colors that match the amp connections. I used a very small jewelers screwdriver to unpin the connectors and had no issues.

Before:
http://farm3.staticflickr.com/2826/9...c29a050cd7.jpg
IMG_4170 by zdr93523, on Flickr

After:
http://farm4.staticflickr.com/3757/9...17bea861c0.jpg
IMG_4171 by zdr93523, on Flickr

The next step was to remove the front input RCA connectors from the amp harness to accommodate the line level inputs and make all of the proper connections.

Note: Please do not post any wiring criticisms or "you should've soldered," etc... If you can splice wiring in an F-16 (you can, and we do), you can certainly do it in our cars.

http://farm8.staticflickr.com/7346/9...1b5a5899bc.jpg
IMG_4173 by zdr93523, on Flickr

Here is the harness with all necessary connections. Note that none of the rear output wires are used.
http://farm6.staticflickr.com/5525/9...dcdc5abd21.jpg
IMG_4176-4 by zdr93523, on Flickr

Once the harness was done, the amp was ready to be installed. I removed the factory amplifier (3 10mm nuts). Then, I connected the amp and performed a functional check and some tuning. I ended up setting the front gain to 1/2 power and the 80hz HPF on. The HPF does not defeat all frequencies below the cut off, it just filters 12dbs off of the frequencies below the cut off. Basically, it makes the bass coming out of my 6.5s sound clean.

OEM amp in top left corner of pic:
http://farm3.staticflickr.com/2875/9...7058795766.jpg
IMG_4178 by zdr93523, on Flickr

Harness connections with OEM amp removed:
http://farm8.staticflickr.com/7455/9...84a9b20c8c.jpg
IMG_4180 by zdr93523, on Flickr

HPF adjustments on the bottom of the Alpine amp (final settings with 80hz filter ON not shown):
http://farm6.staticflickr.com/5483/9...f2c5c9d6af.jpg
IMG_4177 by zdr93523, on Flickr

To mount the amp, I used the OEM amp mounting points and the cable that runs through this area as mounting points for the supplied zip ties. Using this method, the Alpine amp is secure and has airflow all of the way around it, including underneath.
http://farm8.staticflickr.com/7450/9...f1a8d2cfb4.jpg
IMG_4182 by zdr93523, on Flickr

Here's the final pic. I left the wires long and unused wires intact in case I add speakers or remove the amp and want to use it in another car. I may clean up the wire bundle a bit, but for now, the wires are secure where they are. I will cut the zip ties after a day or two of driving once I am sure that they don't need to be tightened.
http://farm3.staticflickr.com/2847/9...97961859a6.jpg
IMG_4183 by zdr93523, on Flickr

Review:
Wiring in the house and in car install took less than 2 hours. Then I sat in the garage for another hour or so listening to it. With the Kappa 62.11s and OEM amp, I could turn the volume up to 60 without distortion. Now, the this little Alpine beast set to a little less than 2/3 gain, I can turn the volume to 30 on some songs. It sounds really good at reasonable volume levels like 12 (used to be 30).

Alpine KTP-445U: Highly recommended!

Nice Write up...if you wore ear defenders more you wouldnt have to turn the volume up so loud in the car to hear your music...will have to check it out when I return from Hell.

Awesome write up, I'm doing the exact same thing except I was going to bridge the amp to get 90watts x2.

Still undecided on speakers (thinking JL C2) but the amp is in the mail. Can't wait!

Already have my wires re-pinned:

http://i54.photobucket.com/albums/g8...psec1e9de4.jpg

I would give it a try without bridging it. I have the 2ch input turned on and with my Kappa 62.11's (75W RMS) the amp is only turned up a little more than half way. I think this amp may be very underrated.

Well I went ahead and installed the same Alpine KTP-445U following the instructions above and it worked! Sorry no pics I was too busy trying to keep the mess of wires organized.

I decided to go ahead and bridge the amp to 2 channel from the get go so I didn't have to go back and deal with all the crimp connectors if I got some higher wattage speakers.

The whole thing probably only took an hour and a half, most of that was figuring out how to connect the 2 harnesses together for the bridged output, in the car only about 10-15 mins to lay everything out and hook it up. It worked the first try.

Had the gain set to half and I scared myself to death it was so loud, reduced the gain to around 1/4 and it's better but will still need some fine tuning since I think it might be too quiet.

I understand the fruits of my labors (and money) won't truly be realized until I get some new speakers, but so far I'm very pleased, you can definitely tell the door speakers are running much cleaner and clearer than before.

Thanks for the information. It helped with my project. I used the oem speaker wire, and converted the oem amp input to rca for my 4 channel amp.

This is going to be old news to some, new information to others, but there is a proper sequence for adjusting gains for cleanest sound. You first need to establish at what volume the head unit itself starts to distort. You do this by leaving the amp gain all the way down and listening to the sound on a high quality recording and slowly turning the head unit up until the sound starts to go bad. Turn the head unit down until it goes away. Make note of the volume. Never turn it up higher than this. Now slowly bring up the gain on the amp until the speakers it is driving blend properly with any other speakers in the car. With luck this will happen before the sound starts to distort. If the sound distorts first, you need a different amp because whatever you bought is over matched by whatever is driving the rest of the speakers.

Edit: This should be obvious but just in case.
Distortion may not be the H/U or the amp. It could also be caused by trying to make cheap speakers play too loud or too low for their design.

But it brings the signal and enough power for a small amplifier, which is nice and helpful.
A bit puzzled about one thing though. Does the head unit drive the rear speakers? They are small so it makes sense but too bad if that's the case because it would have been nice to have those signals here to tap into.

The headunit drives the dash and rear speakers, the amp in the back is for the doors only. The HU should be able to power all those tiny speakers without a problem.

Glad to see this information is helping some people out!

I just installed a sub yesterday. Couldn't (or wouldn't) have done it without this information. This info helped me so much.

Anybody that installed the alpine amp figure out if you wire the high input to the front input will the amp send amplified signal to the rear L/R speaker positive and negative I want to power the rear speakers aswell as the door speakers with this amp.

If I understand the way the car is wired, the rears are powered from the H/U, which means there are no wires involved in this particular harness that go to those speakers.

Does anyone know if the signal going to the amp is truly full range? Is any necessary filtering done in the amp? What I really want to know is if I can tap this signal wire for a sub, assuming I run power wires.

The wires coming from the HU are full range. Not sure what the rear amp is doing to the signal.

The bigger question if you're bothering to run a power wire is why not also run some RCAs from the sub out on the deck? All of these decks have at least a sub-out.

My experience is that the less wiring I run, the better off I am. Plus, if I run an RCA cable, it means pulling up both sides of the carpet to keep it away from the power wire that would run down the opposite side of the car. I'm at an age where my back is cranky enough that the less time I spend bent over my car, the better. I'd much rather sit at my bench making a wiring harness that I can plug in quickly than crawl around in the car.

I used [ame="http://www.amazon.com/gp/product/B00029X1KA/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1"]Metra 71-1761[/ame] and [ame="http://www.amazon.com/gp/product/B0002BEQJ8/ref=oh_details_o00_s00_i01?ie=UTF8&psc=1"]Metra 70-1761[/ame].
On the harness, remote wire is going into right front speaker negative, so I had to cut that wire and reconnect properly.
It's also confusing that the harness on the rear OEM amp has left and right wires swapped out (location wise).
So, you have to go by the OP's instruction. Not by the instruction that comes with the harness.

By doing it this way, you do save time squeezing into tight space. But after I went through all this, I'm pretty sure it would've been easier if I just ran the RCA from the OEM deck. I probably spent 2 hours researching on what harness to get, how to rewire the harness, connecting all the wires, and etc just to save probably 10-20 minutes of time to run RCA cable.

Yeah, but if I run RCA cable then I might as well run individual speaker wires and install a four channel amp and some decent separates and then I'm perilously close to the edge of that slippery slope that ends with my car completely apart and my wife giving me that "I knew you couldn't stop with a sub maybe your son will lend you his car but don't ask to borrow mine" look.

That's very true. I should've done that. Too late now. I ran out of the motivation.

Anyone have a good informative link to what all this car audio terminology means? I don't understand what these methods of bridging, 4-channel to 2-channel, high vs low level inputs, and crossovers actually accomplishes. I have a great grasp of electrical theory, (a 20p20t relay wouldn't scare me in the slightest), but car audio is something that I never cared to delve into.

As far as personal use, all I'm trying to do is figure out how to add some thump for cheap ($200 is what I've allotted myself), and get rid of the door rattles from the lower-frequencies played through the door speakers.

I plan on using [ame="http://www.amazon.com/Kenwood-P-W120TB-12-Inch-Tube-Subwoofer/dp/B004NMLB68/"]this kenwood tube sub and amp combo[/ame], and a capacitor to kill off the unwanted frequencies through the door speakers (though I'm unclear what kind I'll need), but I'm interested in how I could possibly boost the power going to the other stock speaker components utilizing those bridging methods I'm seeing people talk about (if I'm actually understanding that all correctly).

Thoughts?

I finally got around to doing the tuning of the levels on the amp and give it a real world test (80mph on the hwy with the windows down) and I'm very very pleased with the overall results.

One thing I did change was the high pass filter, I had set it to 80hz as a previous poster had suggested but I found the car was lacking bass, I changed it to 60hz and there was a noticeable improvement in the low end and the stock speakers could still handle it.

Overall the whole stereo is significantly clearer, cleaner, louder and has more "punch" even with the stock drivers still in the car. This is a great cheap upgrade (~$170) for the stock stereo that I would recommend to anyone, definitely worth it and essentially plug and play.

Did you use the speaker outputs or HU signal to wire to your sub amp?

I was thinking to take these below and convert to RCA and use as sub output from HU, since BRZ HU does not have RCA out, will this work?

Green = Left speaker signal input from HU [PIN 3 and 9]
Purple = Right Speaker signal in from HU [PIN 4 and 10]