snoofus

Hello,

My amp died recently and I am in the process of replacing the head unit. I plan to run the speakers from the HU amp only and have run wires to the trunk intending to tap into the existing speaker wiring harness there.

Using the very helpful wiring diagram found here:

http://www.lextreme.com/misc.html

I managed to identify three of the four speakers. However on my car the left front speaker doesn't appear to be on this harness. The pink and violet wires do not activate the speaker.

The photo of the clipped connector shows the wires that lead to speakers twisted into pairs. No combination of the remaining wires completes a circuit to the speaker.

I opened the door panel to get a peek at the colour of the wires for the left front speaker and to check it works. The speaker does work and the wires are beige and darker beige. The photo is shows the wires just before the connector to the speaker itself.

I can't see any wires in the trunk that are these colours. Additionally, the remaining wires are a smaller gauge than the wires I have identified as leading to the speakers.

Prior to starting this work I did several searches of the forum for background information and don't recall reading anything about this problem.

I suspect that what's happened is there's some kind of old cellular phone connection is causing this voodoo. Any suggestions other than connecting the wires to the harness adjacent to the door?

Kansas

Those wires to your door speaker look like pink and violet (not beige) to me -- same as shown in the 92 SC Nak wiring diagram I have. My 92 SC Nak diagram also shows the output from the amp to the left door speaker as being pink(+) and violet(-). Hmmm, could all these wiring diagrams be incorrect?

I guess you could use a battery powered test light and a 10-15 foot length of wire to see if you could find continuity between the two left door speaker wires and two wires in the trunk. I did that on my LS when hijacking wires meant for the Lexus phone system to use the wires for another purpose.

I'm doubting that the "voodoo" is from a Lexus cell phone since the diagram shows the right door speaker used for that. Unless maybe somebody installed an aftermarket phone, tapped into the left door speaker and screwed something up.

If you try the continuity trick I mentioned, disconnect the car battery first since some of the wires in the trunk that you probe might be powered. I'm no expert at stuff like this but I've muddled through on similar projects.

snoofus

Hi,

Unfortunately the wires going to the speaker are a totally different colour to those in the trunk. The ones in the trunk match the wiring diagram, and I have tested them with a 9V battery. There's no continuity to the speaker.

I looking at the wiring diagram, I wonder if it's from the UK. It would seem logical to me that the telephone output would be to the speaker closest to the driver.

However that doesn't really help as there's simply no continuity from the pink and violet wires in the trunk to the speaker. I suspect that the continuity depended on one of the components I've removed - head unit or amp.

I'm going to poke around and try to find the harness for the cell phone and see if it has wires that match the colours I'm seeing at the speaker in the door.

Kansas

The diagram I'm looking at is from the ARRC database and is specifically for the 92 SC400 Nakamichi system so I doubt if is for a RHD car. Besides, the parts reference website I use says the first SC sold in the UK or Europe was the 2001 SC430. I checked SC audio diagrams for other model years in the 1990s and they also show the right door speaker being used for the phone audio. Don't know why they chose the right door speaker ... for the 1990-2000 LS400, the left rear door speaker was used for the phone audio.

Both your diagram and mine from ARRC show the same color wires (pink and violet) at both the left door speaker and at the amp in the trunk. That's why I was confused. I couldn't see the pink and violet wires in your photo on the right.

The top portion of the amp diagram shows the inputs from the head unit and the bottom half of the diagram shows the output wires to the speakers. It would seem simple but apparently it's not.

Good luck with this. I'm following this thread in case I replace the Nakamichi in my 00 LS the next time it craps out -- I know it's not going to be easy since adapter harnesses are not available for it either.

snoofus

There are two wires that I would call purple and pink on the white multi connector. They and the blue wire didn't seem to have a home or a purpose when it came time to connect the speakers.

I gave up on trying to figure out where the circuit was broken. I used T connectors to make the connections in the driver's foot well where the harness from the door plugs into the main harness. It was a tight spot to work in, but much simpler than trying to track down the problem.

snoofus

If you're trying to mount an amplifier in the trunk of an SC400, I found a handy mounting spot. There are four threaded mounting points between the right rear speaker and the subwoofer. I believe they're used for the amplifier in cars WITHOUT the Nakamichi sound system.

I found these four mounting points ideal for the after market amplifier. I used a clear piece of plastic to create a template of their position. I then transferred those markings to a piece of plywood.

I used metric bolts with both lock and fender washers to attach the plywood underneath the rear deck. I used some soft putty called dum-dum strips between the plywood and the deck to eliminate any rattling. The bolts snugged the plywood against the putty and the metal deck.

Prior to installing the plywood, I placed two wood screws and washers in the mounting points for the amplifier at the front end of the wood. Then I slid the amplifier's mounting points under the screws and washers. I was unable to tighten the screw at the left front corner of the plywood; hopefully three screws snugged down will be enough to keep the amp in place.

One note of caution for a problem didn't occur to me until it came time to reassemble the trunk panels. The panel that clips in below the rear window was interfering with the plywood I had installed. I had to chose between removing everything to cut back the plywood, or figuring out how to cut in in place. Hopefully you can avoid this aggravation by checking the clearance before you have everything installed.

I decided to use a rotary cutting tool - a type of Dremel - to remove the plywood that prevented the clips from seating properly. This meant the edge wasn't a nice clean cut. However I managed to stain it black to hide the unfinished edge, and it's only seen when the panel is removed. You can see the LEDs on the amplifier through the vent holes in the panel.

In conclusion, those mounting points are quite handy. They enable you to do everything without having to remove the rear seat and panel on top of the parcel shelf.