new to lexus

For those who are too lazy or too busy to read the whole thing, anybody got the wiring diagrams for a 1992 SC300 or at least know where the freaking amp for the speakers is??

And now for the whole story...

I just bought a 1992 SC300 with the Pioneer system ("Lexus Premium Sound" HA! ya right) without a CD changer and have basically finished stripping the interior (doors, interior paneling, backseat, etc.) to install the stereo of course.

I have determined that of the four plugs in the back of the deck (from driver side to passenger side), the first (10 pin) is for the subwoofer, the second (6 pin) is for the rear speakers, the third (10 pin) is for the front speakers, and the fourth (blue 6 pin) is for the volume control, although I don't know which wires within each do what.

I also found the Amp in the trunk (passenger side) in which the only connection is a 10 pin plug. (First of all, I don't understand what its doing without seperate input and output plugs but anyways.) After disconnecting that plug (leaving the amp and plug each connectionless), the stereo continued to work with the exception of the subwoofer.

I saw a post earlier,

"Did you know that all speaker leads goes back to the factory amplifier? well at least they do in the SC300. I found my factory amplifier in the lower right hand corner of the trunk, under the panel. Finding this amp, will save you time of removing panels,rear deck, etc...to reach the speaker cables. "

which makes me wonder if there is another amplifier? The one I found was located in the same place described above and I can't find another amp anywhere. If this is the only amp, do you know which wires do what, or at least which speakers that it controls? I would have thought that if it controlled any of the speakers, they would have decreased in volume to an extremely low level or no sound at all after disconnecting the amp.

I have been struggling with this for a couple days now and have read every post on every message board I could find (including the old Ladman's forum now hosted on EZboard although many posts alluded to the history link for the valuable information which is now sadly deceased).

I am almost at the point where I might just go out and pick up a new head unit just so I can get a preamp output!! but I really don't want to do that because I don't believe in destroying the already perfect interior look of my heavenly new lexus! (plus a non-stock head is an invitation for thieves who have already helped themselves to double servings of my last car and system =(

Any assistance that any of you could provide would be greatly appreciated especially because I don't want to take it into a shop and be laughed at as another failed do-it-yourselfer, plus I don't think they'd do that great a job anyways.

Thank you very much in advance,

Kamil


p.s. sorry for the long post but the sooner I can wrap up my stereo install, the sooner I can join you all out on the Southern California roads! (and who knows how many other states I might joy ride through!)

gadgetSC

Kamil, I have a service manual and hope to get a chance later to post some info on the 300 stereo. As far as you locating your amp's. The amp that you found is for the sub. Looking at the wiring diag in the manual....Shows that the only external amp is for the sub. The other speakers are powered by an internal amp in the head unit. Short of scanning the whole page, I will try to help if I can.

If you can access the back of the head unit.....

From the back, left to right

Connector "B" Connector "A" Connector "C" Connector "D"


Connector A Pins
1. FR + (front right speaker)
2. FL +
3. ACC
4. +B
5. FR -
6. FL -
7. Ground
8. not listed
9. AMP + to power antenna
10. ILL + (for head unit lamps)


Connector B
1. Vol C
2. PWR
3. SGND
4.
5.
6. Vol +


Connector C
1. RR + (right rear speaker)
2. RL +
3. RR -
4.
5. ILL -
6. RL -


Connector D
1. RU + (to sub amp pin 1)
2. Mute
3. TLMT (for telephone receiver)
4.
5. RU - (to sub amp pin 5)

I hope you find this useful.

gadgetSC

new to lexus

gadgetSC,

Thank you soooo much. If you're ever in Cali and need anything, don't hesitate to contact me and I will do my best to accomodate whatever you need.


Now for a more general question to everyone. Obviously I need to get either a LLC or an amp with LLIs but from where should I get the signal to input to the amp?

I would prefer not to lose balance and fader controls if possible, although I realize that it might be something that I have to sacrifice, but I would like to maintain some sort of soundstage!

Do LLCs and LLIs have more than one input? (i.e. one from/for each speaker/channel to maintain the soundstage)

Also, if I'm not mistaken, the rear speakers are woofers but is the signal going into them the full range? or is it cut out by a crossover somewhere along the line (hopefully not in the head)?

It would be a major pain to use the signal going into the front speakers as my input to the amp because it is just wayyyy too crowded down there under the kick panels and impossible to figure out what is what. (Plus my amps are going to be in the trunk.)

And finally, the input to the sub amp: pins 1 and 5 are "RU+" and "RU-". What does RU stand for? Is that a preamp signal? Does that only carry low frequency signals? or is that a full range signal going into the amp?? (with a crossover in the amp) That would truly be a blissful solution!

Thanx for the help guys!

Kamil

CmputerWiz

I've got a 93 SC300, and it also has the amp beside the sub. There is ANOTHER amp in the trunk of mine (or rather, was another). It's under the CD changer. If you pull out the floor of the trunk, you'll see it under the changer. All the speakers (minus the sub) wire from this point. I'm not sure if all have this, but mine did. I had the pactory Pioneer with 12 CD changer....not the Nakamichi (sp?).

Hope this helps!

SR

vj604

this is right. there are 2 amps. the one under the cd changer in the trunk is for the speakers while the one under the rear deck is for the factory sub.

YuuDawg

I have a '96 sc300 with the premium sound system
is this the nakamichi or the pioneer sound system?
is there anyway i could get a scan of the audio wiring in the shop manual?
where'd you get yours anyways, i've been tryingn to get my hands on one, but it seems impossible.

new to lexus

CmputerWiz and vj604

>>Pioneer system ("Lexus Premium Sound" HA! ya right) without a CD changer

I know that the system with the CD changer has 2 amps, unfortunately mine is without the CD changer and does not have the second amp which makes this seem that it is going to be a very tedious job. I wish there was one wire that carried the signals for all the speakers! (hmm...like a preamp output? lol) There are probably very few of you out there without the second amp and it is those who I am looking to for assistance. Am I really going to have to run 20 some wires back and forth throughout the car!?


YuuDawg
You have the pioneer system, with or without the CD changer makes a big difference. And gadget sc already posted the pertinent details that you would get from a scan of the page (probably easier to read his way anyways!) And the manuals are very easy to find, just extremely costly!
Kamil

933005spd

There are some good juicy details on this topic on some earlier posts. You may also want to check out my site and go to the Stereo Hackensack link. I have used the factory head unit with upgraded amps in a 300 (premium) and 400 (Nak).

lexus site

new to lexus

933005spd

thanx for the suggestion, although as I said, I've already read every single post on this and as many other sites as I could find. As a matter of fact, I have previously been to your site as well and you had an external factory amp for the speakers whereas mine does not.

By the way, sorry bout your car. =(

Kamil

DoubleWhoosh

What exactly are you trying to do with the audio system?

I can provide you with whatever information you will need, but it would help to figure out what you are trying to accomplish.

Todd M.
TM Engineering
http://www.tmengineering.net

gadgetSC

Hey Kamil,

The wiring diag doesnt say if the RU signals are full range or not. They are the pre-amp inputs to the sub-amp. The diagram doesnt show an external crossover for the rear speakers, just a straight connection. I cant find anything in the manual with internal detail of the amp or head unit. Just the wiring and connector diagrams. Sorry I couldnt help more.

gadgetSC

new to lexus

gadgetSC

Don't apologize, You helped more than you could possibly imagine!

Thanx!

Kamil


Does anyone know if the rear speaker inputs or the RU inputs are full range? If I hook up a two way speaker (i have some old kenwoods lying around) or the stock tweets since I'm tossing them anyways to the RU outputs and I can hear vocals, would that mean that the line is full range? (What does RU and BU stand for anyways?)


p.s. If anybody wants the Kenwoods contact me via PM. Should be in Cali cuz otherwise they ain't even worth the shipping! HAHA. They're brand new 2-way 6" (i'll check the specs if anyone wants to know)-- I never got around to building a housing for them in my last car so they just sat around the garage still in the box!

new to lexus

gadgetSC,

Could you also tell me the diagram for the plug going into the subwoofer amp?

Its a 10 pin

I would really like to use the whatever wires I could from it (i.e. Sub Input, remote-turn on, etc.)

Thanx!

If anybody else knows the answer you could reply also, but remember its a 1 amp pioneer system without cd-changer. very rare!

gadgetSC

Kamil

The 10pin sub amp connector:

1 - RU+ (preamp signal)

2 - MUTE

3 - +B (12v Battery Fused)

4 - ACC (Ignition Switch Fused)

5 - RU- (preamp signal)

6 - AMP (also tied to pwr antenna motor)

7 - E (Ground)

8 - Not Used

9 - WF- (Signal out to woofer)

10 - WF+ (Signal out to woofer)

Hope this helps

gadgetSC

Jmai22

what do you mean rear deck. can anyone tell me where i can find my subwoofer amp at. i found one under my cd changer but don't see one for the sub