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1995-1997 LS400 Aftermarket Radio Install Utilizing Stock Amplifier for Pioneer Radio
My 1995 LS400, Came with the Pioneer head unit and 6 Disc changer, NOT NAKAMICHI! My objective was to utilize all the stock audio speakers through the stock pioneer amplifier with a new head unit. I have done extensive research and most people utilize a bypass and add the new equipment. I personally have had bad experiences trying to utilize stock speakers with new head units and I really like the quality of this particular stock system. Also, I could not find to save my life an easy write up showing what is constant positive (12+), Dimmer Wire, ACC Wire and spent quite a while figuring this all out .
DISCLAMER: If you are not comfortable with wiring a radio or cutting the stock harness this write up may not be for you. Please see the attached wiring diagram to this write up to use as reference. I am not an electrician/audio installer this is just a general guide compiled from the internet to install an aftermarket radio in a 1995 LS400.
If you want the DIAGRAM in the pdf format I have attached it to this post at the very bottom where it says "attached files" labeled radiowire.pdf
The key part of this build is to utilize the stock amplifier and to do so you will need 4 RCA Jacks. I was able to obtain a male/male set at the local thrift store for $3 (you may have this laying around). The RCA cables will need to be cut and stripped to be used for wiring. The RCA plugs will take place of all the speaker wires (since the feeds incoming on the RCA is amplified). There also is not a need for Hi/Lo converters that is only for stock head units to after market sub woofers.
Looking at the pictures of the plugs in the wiring diagram, you will only be needing to use plugs "R 2 B" and R 3 C GRAY". I have also marked out the +12v, ACC, Dimmer Wire and Amp On.
You will be cutting the wires that go to the factory plug and soldering on RCA Jacks. With your RCA plug with the 4 male ends you will need to cut off with about 5-6 inches of wire still attached. This is what the RCA should look like modified to be RCA>speaker wire (strip the center wire too not shown).
Here is the wire combo for the RCA to stock harness using the A plug. NOTE: Center of RCA is positive outer is Negative.
Take a White RCA Jack and solder the Green wire from pin 14 of plug A to the negative lead of the RCA Jack.
Solder the Red wire from pin 5 of plug A to the positive of the RCA jack. This is for the Rear Left speaker.
Take a Red RCA Jack and solder the White wire from pin 7 of plug A to the negative lead of the RCA Jack.
Solder the Black wire from pin 2 of plug A to the positive of the RCA jack. This is for the Front Left speaker.
Take a White RCA Jack and solder the Green wire from pin 13 of plug A to the negative lead of the RCA Jack.
Solder the Tellow wire from pin 4 of plug A to the positive of the RCA jack. This is for the Rear Right speaker.
Take a Red RCA Jack and solder the Red wire from pin 6 of plug A to the negative lead of the RCA Jack.
Solder the White wire from pin 1 of plug A to the positive of the RCA jack. This is for the Front Right speaker.
Now these are ready to plug into your new head unit. Cannot stress enough DO NOT just skip wiring in RCA's and just wiring them into the Speaker wires coming out of your new head unit! Again, those wires are Amplified wires that are meant to go to un-amplified speakers. Just tape those up because they are unused.
Photos of the harness after wiring:
There you go! Awesome factory sound with a bran new head unit! Hope this helps with future installations for other LS400's out there!
Last edited by LexusNAZ; 05-22-17 at 10:44 AM.
Reason: making better notes for the attached pdf at bottom
not all RCA outputs in modern headunits are preamp. Some newer headunits let you select if the wired outputs are amplified or not.
This needs to be tested on a 98+, the multiplexing changes a lot of things.
IIRC any non-stock system using the factory amp loses all fader/balance controls. Is that true in your case?
Yes, you are correct regarding the RCA and 98+ models.
- Regarding the RCA you will need to purchase a head unit that has RCA for AMP hookups. If you get a good quality nav/radio unit it should be included but you will need to check.
-I can only speak for my generation of LS400 (95-97) but the RCA retains all factory functions fade/balance along with subwoofer as well. I will double check but when I used the fade feature it worked yesterday.
If you have a newer model or Nakamichi this writeup will most likely not work for you.
First, this is my first post, as I am, as of yesterday, a first time Lexus owner. 1996 ls400 in amazing condition with 150k miles. It took me about 2 months and multiple CL appointments to find this one, but I am beyond stoked.
Only thing is the stock stereo. It's working, but has a bad LED, and I have become reliant on bluetooth for podcasts and car meetings.
I spoke with a stereo installer today about the method outlined above (pre-outs to the factory Amp) and he seemed to think it would be problematic in that: (1) the pre-outs from the new head would be providing too much power to the speakers through the factory Amp; and (2) that the factory sub wouldn't be able to be looped in to the system, or that it simply wouldn't be getting enough power to compete with the now over amplified speakers. He was also concerned about floor noise in the system.
He wasn't trying to up sell me anything, and I was already paying him for the install, so I'm confident in his honest motivation. His suggestion was that we just bypass the Amp, as the new head will provide plenty of power to the speakers, and to wire in a micro Amp to the factory sub, which should keep the sound profile, more or less, as it was stock.
Thoughts on this? My understanding is that the pre-outs should be preamplification, thus there would be no power issues, but I honestly don't have enough knowledge in this area.
First, this is my first post, as I am, as of yesterday, a first time Lexus owner. 1996 ls400 in amazing condition with 150k miles. It took me about 2 months and multiple CL appointments to find this one, but I am beyond stoked.
I did this about a year ago due to a dead factory headunit, plus added a bluetooth receiver via the AV inputs..... So glad i didn't spend the extra time and money on re-doing the system. The pioneer speakers, sub, and amp still sound amazing even after 22 years.
As far as functionality, I am not sure since mine was a 95. The reality of it is if you wire your new head unit to your stock speakers it will be horrible. like I did to the oem amp and speakers you will have much better quality than if not. You otherwise need to run all new wires and speakers for your system. There was another method or thread on how to hook into the amp for a newer year car (2000). This method is much more complex and requires relays. Unfortunately, the thrift store aux cables and radio mod I did was easy and sounded ok with some tweaking of the HU . This method is not perfect but it will be the best way to keep an oem setup. Also, you can add in an amp and sub if you want more bass or a combo unit like a bass tube.
I intend on attempting this with my '98. It looks like the pin-outs are a bit different and there are only two channels going into the amp instead of 4 so I will likely lose front/rear fader. I'll post back here if I'm successful. I do wish I could find a wiring kit that would fit so I could just plug into the old harness instead of cutting it.
I have a 95 (with nak) where the previous owner bypassed the factory amp and powering the four speaker directly from the head unit so I lost the sub.
Now that I look at this, if the factory sub is still working maybe I could take the head unit's sub out and feed it into the factory amp to drive the sub.... 🤔
I just wanted to give a quick update on this thread. There is a kit from Japan Beat-Sonic SLA-21A you can buy for under $100 and have it imported from Japan via buyee.jp or similar. Or buy it from the American Beat Sonic website
Nice car and welcome to the foruml!! The second gen LS400 is an amazing car!
I have to wait but I have a 1994 Celsior waiting for me to come over from Japan:
Originally Posted by Everett464
First, this is my first post, as I am, as of yesterday, a first time Lexus owner. 1996 ls400 in amazing condition with 150k miles. It took me about 2 months and multiple CL appointments to find this one, but I am beyond stoked.
Only thing is the stock stereo. It's working, but has a bad LED, and I have become reliant on bluetooth for podcasts and car meetings.
I spoke with a stereo installer today about the method outlined above (pre-outs to the factory Amp) and he seemed to think it would be problematic in that: (1) the pre-outs from the new head would be providing too much power to the speakers through the factory Amp; and (2) that the factory sub wouldn't be able to be looped in to the system, or that it simply wouldn't be getting enough power to compete with the now over amplified speakers. He was also concerned about floor noise in the system.
He wasn't trying to up sell me anything, and I was already paying him for the install, so I'm confident in his honest motivation. His suggestion was that we just bypass the Amp, as the new head will provide plenty of power to the speakers, and to wire in a micro Amp to the factory sub, which should keep the sound profile, more or less, as it was stock.
Thoughts on this? My understanding is that the pre-outs should be preamplification, thus there would be no power issues, but I honestly don't have enough knowledge in this area.
You need to modify like i did initially (not perfect but utilizes stock amp and speakers). Or you can do an amp bypass or full re-wire with your own system speakers and setup. There is the JDM beat-sonic kit that is plug in play and requires no modification to the wiring harness of the car.
As for the installer he does not know what he is talking about since the pre outs just send a signal to the amp (low power) then the amp boosts to the input level the speakers can handle (high power). I did not have distortion or a blown system due to the method I used.
Also, you cannot run the subwoofer or the stock speakers without an amp since they will sound horrible. You cannot use an aftermarket amp on the stock subwoofer since it will blow up and sound like crap. One needs to either use the system with the factory amp or just install an aftermarket system with an aftermarket amp.
Just depends on what level of audiophile you are or how deep your pockets are. The stock pioneer system for being as old as it is has very nice sound. This mod I did was cheap and the cords I used I picked up from my local thrift store. I just ordered a beat-sonic kit for this year of car from Japan its in the mail now.
Here is a diagram of an amplifier to help clarify what is really going on:
05-22-17, 10:38 AM
1995-1997 LS400 Aftermarket Radio Install Utilizing Stock Amplifier for Pioneer Radio
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