Wiring up radio for 2004 Tundra Double Cab w/ JBL system

Need help finding how I should go about connecting my new stereo without having to splice the factory connectors.
I followed this forum but the Metra harness

$8 70-1761 Radio Wiring Harness For Toyota 87-Up Power 4 Speaker

70-1761 doesn't fit mine.
https://www.tundras.com/posts/2992921

These are the wires that came out from behind the radio.
The amp is located towards the back behind the kick panel on the driver's side.

 

I have 04 LTD DC also and the 70-8117Amp Bypass Harness is what you need if you are indeed bypassing your harness. I personally went thru Crutchfield for everything and the 70-8117, is their Part # 120708117.

Metra 70-8117 Amp Bypass Harness Connect a new car stereo and bypass the factory amplifier in select 2003-07 Toyota vehicles at Crutchfield

The post you linked to and related picture is correct and important part I circled in red.

Do you have steering wheel controls and are you planning to also include those in your install ?

 

If you’re not bypassing the amp, you’ll need a Crux or similar adapter (which will also retain steering wheel controls if you have them).

best thing is to go to Crutchfield’s website and shop for your truck and the radio you have and see what they state for the needed parts for installing

 

Does amp look like this on back wall of cab drivers side?

 

So, I ordered everything for the truck including the steering wheel control kit but I guess the question I have is how would I get started on wiring up the OEM connector to the new stereo. I think the part that is stumping me is the fact that there is a factory amp that I need to bypass.

• https://www.crutchfield.com/S-CATO5ccfq8d/p_500ILX507/Alpine-iLX-507.html - The stereo I ordered
  
• https://www.crutchfield.com/S-KEWgBKvVk8B/p_113X8025/Kenwood-Excelon-X802-5.html - The amp I ordered

I ordered the amp bypass harness that you had linked but I guess the part where I'm stumped is where/how would I get started and whether there is a plug-and-play wire harness for the OEM wires that is located behind the radio.

 

Yep, my amp looks exactly like that.

 

Amp bypass harness:

$38 70-8117 Factory Amplifier Harness for 2004-Up Toyota Vehicles with JBL Sound System

70-8117 from Metra includes two connectors. If I remember right, the wide one plugs into the wider connector you see at the amp. You then route the dozen feet of wiring up to your head unit, those are your speaker leads to attach to your Alpine harness (or, er, to your Kenwood amp, forgot about that). The other, smaller one, again if memory serves, plugs into the big box connector someone's Neanderthal already cut up inside your dash like an asshole, it provides power etc.

I don't think you need 70-1671 if you have a rear-mounted amp - if I said you need that in some piece of text on here, LMK where, I need to edit that. 70-1671 is only for people with dash-mounted amps, or no amp at all.

 

Oh, and for the amp ...

You'll need an amp wiring kit, ideally 10-12awg positive wire, which you'll route through the firewall, and FUSE IT no farther than 12-18" from the battery.

Kit needs to have an equally beefy ground, which you'll want to ground out to a beefy, unpainted surface.
Kit should have a remote turn-on lead also, but you can buy RCAs these days that have a turn-on lead attached.

Try to get GOOD copper, you don't want to skimp on your amp wiring kit by buying tinned copper. Kicker makes awesome kits.

MOUNT YOUR AMP SECURELY, IN A WAY THAT IT DOESN'T BECOME A PROJECTILE IN A COLLISION. You don't want to have ankle surgery because you opted to velcro your amp to the floor. Don't be that guy. If you need to, liquid-nail a thin 1/4" tack strip to your floor, let it dry, and screw into that to avoid sheet metal damage.

Wiring as follows:

• Power wire from battery to amp
• Ground wire from amp to a GOOD grounding location nearby
• Signal input from radio: Run RCA from your amp to back of head unit, along with the turn-on lead ("remote turn on" wire on most harnesses incl. Alpine is dk blue, sometimes dk blue w/wht stripe)
• Signal output to speakers: Use the speaker leads from your Metra amp bypass (from the wide connector you plugged into amp)

Make sense?

 

PS - if you have steering wheel controls (I'm not seeing the harness but my old eyes are going south) there's a plug-and-play kit to keep those controls too.

Update:

I went back into the amp thread and updated the imagery to maybe help others in the future. I didn't realize how confusing I was probably being with it, and I also had a contradictory typo in there. This is the new graphic.

 

Oh - and one point to make - I'm pretty sure this is the Fujitsu amp, not the JBL amp.

JBL amp is a bit longer and skinnier, and has a wide rectangular white sticker on the broad side with an orange JBL box logo on it.