How to use the OEM amp Wiring

[RandomHero]

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


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.



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:



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]

[RandomHero]

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

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

[Chewie4299]

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

[crazyfrenchbiker]

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

[mashal]

what are you trying to do ?

[RandomHero]

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

[f0rge]

Originally Posted by Chewie4299

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

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?

[RandomHero]

Originally Posted by f0rge

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.

[f0rge]

Originally Posted by RandomHero

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?

[RandomHero]

Originally Posted by f0rge

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

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.

[f0rge]

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.

[RandomHero]

Originally Posted by f0rge

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)

[f0rge]

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.

[RandomHero]

Originally Posted by f0rge

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!