Stock head unit wiring

Alright guys I’m lost and need help. I am trying to install subs in a 2001 tundra. I don’t want to have to get rid of the stock head unit. My problem is that the stock head unit does not have amp hookups. I purchased this scosche loc2sl adapter just thinking I could splice it in to my original wires. My question to you guys is this, do any of you have a diagram showing what each of these individual wires shown below means as far as which would be (LF+)(LF-)(RF+)(RF-) and so on and so forth?

Thanks.

 

https://www.tundras.com/attachments/2001-tundra-ewd429u-pdf.543918/

Scroll to page 200.

And for f's sake please use a non-invasive tap like Posi-Taps.

 

So usually I'd say do not cut into a factory harness, however that single plug harness goes down to a factory amp that sits behind the climate controls that is easily replaceable and not worth much (I have one in a box in my basement). Only problem is that the wires hooked up to the back if the radio are non amplified signals out of the factory radio so they may not give you the output you need. I think LOC's want the same signal your speakers themselves are getting. You can pull that amp out (follow the wire down to the amp) and you'll see where the normal Toyota style plugs hook to that amp and those would probably give you the right signals for your LOC. Would be easy to decode wires from there.

My recommendation though is to pull your signal from your rear speakers directly and put the module somewhere you can access it. And splice into the speaker wires since they are pretty simple. Only problem there is that you have to pull wire from both rear doors and hook to the LOC.
If you were to pull from the rear speakers you can power your LOC off of your amp power wire with a fuse.

Your best option overall here would be to ditch the factory radio and go aftermarket but if you are dead set on keeping it this is what I got for ya.

 

Adding a little info onto what Nick said already, so it's painfully clear.

You may think your system isn't amplified already. But here's what he's talking about.

The earlier models had an amp behind the climate controls, in the spot of the yellow arrow in the left pic. Nick knows this because of the rubber-wrapped single harness circled in blue in the right-hand pics, which you'll see the other side of in your pic, the rubber is the giveaway. Basically, the system is sort of logically reversed from what you may expect. That rubber-wrapped harness sends audio signal from the head unit to the amp, and is also how the head unit receives power from the amp. The red circle in the right-hand pic is the amp's power/ground feed with front speakers on one plug, the rear speakers on the other plug. For more technical schematics/details, see this post. For a rough decode on the wires, see this post. I'd personally try to tap your PAC off the outbound from the head unit for a non-amplified signal, versus the rear outputs on the smaller amp output. But again. USE A POSI-TAP, not some bullshit other type of tap that'll dick up your factory wiring. If your truck doesn't have this amp setup as described, by all means, tell us we're wrong. But normally the non-amplified trucks have two plugs on the back of the OEM head unit, IIRC.

 

I'm pretty sure LOC's usually want the same signal you are sending to your speakers. Line level input is usually how they are setup. Not sure the sub would get loud enough if pulling signal before the amp.

 

Most PAC/LOC units I worked with advertised as low as 0.5w - 1w input on the low end, but could accept 10x-20x that. I'd cautiously assume the OEM HU is outputting at least that to the amp. I'm making that assumption because they're using a non-shielded standard copper conductor to push the audio signal from HU to amp.

My assumption could be wrong. (I doubt it, but I'm open to the possibility)

The beauty of using Posi-Taps to tap into the line is they simply pierce the casing, so removal is super non-invasive. In the event Toyota is indeed sending an ultra-low output across the line from HU to amp, it's simple to un-tap, leaving only a small piercing mark on the wire sheath that can be sealed with liquid electrical tape.

I'm assuming OP could test the output signal. Would be cool to know the result.

Generally speaking, though, OP can also look at the specs for the converter box they choose to make sure they're getting something accepting lower input levels.

 

I just put an aftermarket 5 channel amp in my '04 DC (JBL with factory amp behind the back seat). So far I only have it driving an 8" sealed sub, but I pulled the signal from the head unit. It works fine feeding a low level signal into the amp but what I found is that the head unit volume control does not change the volume of the subwoofer so I have to modulate that with new amp remote. I think volume changes coming from the head unit are applied to the signal inside the factory amp. Once I connect my door speakers to the new 5 channel amp I'll have to adjust volume from my smart phone since I'm only streaming Bluetooth audio anyway through a head unit adapter.

 

Interesting, I've never seen that before. I'm curious, is it only true for bluetooth streaming, or does it happen with radio/tuner also? Which PAC/LLC/LOC did you choose?

Only reason I ask is because an old Kenwood receiver I had (~6 years ago, so fairly current tech) was the same way with bluetooth audio. Bugged the hell out of me.

I've also seen different converters work differently. I'm wondering if one with a wider range of low-end sensitivity would help, and/or I'm wondering if maybe the head unit is using an added wire to the amp to adjust gain? But I'm not seeing that in the EWD.

I typically like PAC's and Scosche's products for easy no-power-required units. But you should know, you can also drop in simple line driver line the PAC LD-10 to bounce the signal. Or just tap off leads from the OEM amp instead.

FYI, some converters need to be tuned for output. Here's one example from PAC: https://catalog.pac-audio.com/index.php?controller=attachment&id_attachment=40

 

I have a AUX interface adapter

Yomikoo Auxillary Adapter, AUX Car MP3 Player Radio Interface AUX in Adapte 3.5mm Aux Interface for Toyota (6+6) Pin Connector 2005-2010 Camry 2005-2011 Corolla 2003-2010 RAV4

like this that plugs into the CD Changer port with an Anker Soundsync A3341 Bluetooth receiver.

The 5 channel amp is a

$160 Soundstream PN5.640D Picasso Nano 640 W 5-Channel Class D Digital Car Audio Amplifier

Soundstream PN5.640D which supports both high and low level inputs, but you can't mix and match them.

I did test the FM radio and the volume control doesn't work for the new amp/sub on that source either.

I attached the wiring diagrams that I used for my system.

 

Ah. Yeah, that's not a line-out converter in the traditional sense, like the OP would be using.

I'm guessing that's a shortcoming of the AUX adapter you're using, or maybe the Anker BT device, or maybe it's a byproduct of how the CD changer port handles audio in/out. Technically, I wouldn't expect the CD changer/AUX port to actually have (or respect/need) volume control. I would expect the HU would expect a "flat" signal to/from that source.

 

Oh my, cassettes and cd changers...
Y'all are making me feel nostalgic, all warm and fuzzy from a better time...



Hell, I go way back.
My first aftermarket tuner..



Sorry for the thread drift.
As well these pics make me miss my 2005 DC....

 

I'm just happy Toyota has consistently been using double-DIN openings for so many decades.

I can't tell you how frustrated I've been in the past with vehicles I've owned with 1.5 DIN openings from the factory. For a short while there, some manufacturers were offering 1.5 DIN head units, but they're unobtanium now. So many systems in my past were limited to a single-DIN receiver with dumb-looking half-DIN pocket underneath it that barely fit a CD jewel case, much less two. I honestly believe that's what led to the single-DIN-head-unit-with-foldout-LCD craze that was big for a while.