wwillmon

Hello there.
I am trying to install an aftermarket headunit in my girlfriends car. It is a 2002 GS300 with just the regular stereo (no navigation). I did notice it has a sub, or something in the back deck? so maybe there is an amp?

I have searched and searched and found 3 different wiring diagrams for the car stereo with each one saying something different regarding the color codes for the wires. I tried hooking it up last night and couldnt get any power to the stereo. Can anyone help me and let me know if there is something i need to do?

I just cut the plug from the factory stereo and was trying to wire directly to the wires that are there, since i have seen that there is no wiring harness for these cars. I am super lost and dont know what i need to do to get the stereo working and turned on.

Thanks for any help,
Justin

blacksedan

iTrader: (4)

I don't think you've taken the time to read through the plenty helpful threads on this topic...

But in short, you get your 12v constant and ignition source from behind the radio. Then, the speaker connections are from the amp behind the glove box to the right. When installing aftermarket stereo, you're bypassing the factory amp and of course you will lose the factory sub. Link for the DIY is below:

https://www.clublexus.com/forums/gs-...iy-add-on.html

wwillmon

Okay so if im seeing it right my 12 volt source will be the gray wire, and not sure on my other wire? And then i need to ground my wire from the aftermarket radio and then catch the speaker wires from the amp which is behind the dash?

wwillmon

I read the thread you posted and i really appreciate it. My only other question is.....It looks like i take the red wire from the aftermarket radio and connect it to the gray off the factory stereo harness. Now where do i connect my yellow power wire from my aftermarket stereo? Seeing as it is my constant i believe and red is my switched source wire?

Then just ground it like shown in the picture? and then ill tap into my existing speaker wires from the factory amp? And this will essentially bypass the factory amp and make the factory sub not work as well correct? Or am i completely off?

PlatGS3

yes your factory sub and 6 disc changer will not work anymore.
but i dont remember what I did with the wires except run wires for the speakers from the factory amp in the trunk all the way to the front. but i remmeber i had a memory problem and had to wire some wire another way.

wwillmon

Okay im sure i can figure something out, if you happen to remember or anyone else knows let me know. I figured her car would be no different than wiring up a regular stereo but, man i was wrong haha.

So basically just look for the amp behind the glove compartment and thats where all my speaker wires will be tapped into, as well as my ground and then probably my yellow wire will go somewhere over there as well.

Tank

iTrader: (19)

First off, what kind of radio do you have? the pionner or the Nak?
second you CAN hook up you factory SUB, you just have to feed off the connections BEFORE it goes into the AMP (if you have one) let me know what radio you have and I will photo copy the correct page from my OEM wiring diagram manual.

wwillmon

Okay thank you, it is the factory pioneer radio. Just replacing with a single din kenwood. I understand about hooking up the factory sub, im just not even sure if she wants it. I also catch the speaker wires before they go into the amp correct?

But if you could let me know. Thank you.

Tank

iTrader: (19)

Yea, you can run your SUB wire directly to the radio (if it has that option) I'll look up the scematics for your radio tonight (manual is at work) when I go in and get that to you. that way your know for sure which is wire which. now I'm sure there are dozens of pieces of info on the subject on here but since your having a bit of trouble anyway it's not prob to help.

wwillmon

Okay i really appreciate it, one last question. Do i need to unplug the connections going into the amp once i get the speaker wires connected or can i just tap into those wires and leave everything connected?

Tank

iTrader: (19)

Sorry, but I just realized you have an 02' and the manual I have is for a 98'. However, the scematics I have do show an amp for the Non-Nak (Pioneer) system. it shouldn't be any different for an 02' (02' owner's please chime in if I am wrong..) I don't see Lexus re-wiring the whole radio system from year to year without a really good reason. But to answer your last question I'm going to tell you what I did before I reconfigured my whole system and dropped a Z1 and an 5 Channel in my car.
First off your AMP will not work once you change out that head unit, reason for this is the AMP is connected via BUS power and once you disconnect the harness containing this connection the AMP will have nothing telling it to turn on/off. or any power for that matter.
After all your connections are done, you need to disconnect the AMP.. you will be tapping into the SPEAKERS including the SUB at the wiring harness that connects them to the AMP this harness needed to remain DISCONNECTED. you don't want anything connected that doesn't have to be and cause a short. Remember, you must proceed from here on at your own risk, I can try to guide you and help but it must be your decision to continue. with that said onward!

First off not insulting your intelligence but just to make sure you need to have your three POWER connections correct; ACC, ILLUMINATION (ILL) and main power (BATT)

Tank

iTrader: (19)

The ACC and the BATTERY power wires are colored as follows: BATTERY: Blue (L) and Yellow (Y) (Don't ask me why, thats how the guru's @ toyota coded them..lol)
ACC: gray (GR)
(upper left hand corner of pic)
test these wires with tester to Make sure.
ACC should power up when the key is switched to ACC
BATTERY (12v) should ALLWAYS have power.
(the other ACC wire (pink/blue) is for POWER from the RADIO to the AMP will not have power unless the harness is connected to the radio)

Tank

iTrader: (19)

Now for the ILL wire (ILLUMINATION) your gonna have to test out (with your tester) each other wire on the harnesses that goes into the back of the RADIO. A good way of doing this is to attach a test lead to every wire and turn on your PARKING LIGHTS. once you turn on your lights. that wire your testing should power up. and volla! there's your ILL wire connection.

Tank

iTrader: (19)

SPEAKERS..
REAR and SUB should be tapped into on the wiring harness that is connected to the AMP.
as you can see in the pic SUB: Light green/Black (+) Light Green/Red (-)
REAR DOOR/RIGHT: Red (+) White (-)
REAR DOOR/LEFT: Black (+) Yellow (-) now here's the tricky part this speaker is connected to the TELEPHONE speaker relay (lower right corner of pic) I don't know if this is powered or not so if the connection doesn't work at the harness your gonna have to go directly to the speaker.

Tank

iTrader: (19)

FRONT SPEAKERS:
same thing, make your connections at the wiring harness to the AMP.
FRONT DOOR/RIGHT Light Green (+) Blue (-)
FRONT DOOR/LEFT Pink (+) Violet (-)