'94 Ls 400

[Ross W.]

Hi all

Been quite awhile since I last was here. Been really busy.

Anyway, the factory Nakamichi audio sys. conked out about 18 months ago, which started me saving for a new system. I bought a Metra double-DIN install kit for it. The supplied harness adapters don't fit the chassis harness plugs. I've been trying to reach their tech dept but I can't get through. I'll send them an email later.

I've heard conflicting stories that the Nak system has an outboard amp(s) OR it's all in the head unit. Either way, nothing fits! I'll probably end up wiring up the new unit the old fashioned way, but running speaker cables into the doors and power leads from the batt. does not look like a straightforward job. I'll be using the new unit's onboard amps for now.

So if anybody has any advice for me, I'd really appreciate it!

Thanks!

[RDM]

It's been ages since I took one apart, but the Nakamichi deck does use an external amplifier for the entire system. You don't have to run wires though, you can match up the deck's preamp outputs to the trunk area and just tie them together to the speaker leads, IE if you have a white and black matched pair in the front, use that same set in the rear and tie it to a speaker pair in the trunk. The deck has four outputs total, so you can use them all to run the four door speakers (the tweeters are wire parallel to the front door speakers). The subwoofer though won't work without an adapter, there is a company that offers an interface harness but it's like $200.

That would be far easier than running your own wires, and on the point of body repair it's better because *if* you have to remove/replace a door you don't want to deal with cutting and then splicing your wire you ran, the OE door harness unplugs in the car.

[Ross W.]

It's been ages since I took one apart, but the Nakamichi deck does use an external amplifier for the entire system.

Thanks!

I did track down the correct harness adapter last night; Metra 70-8112 @ Sonic Electronix, $14.95, and I should have it in a few days. It's designed to have an aftermarket head-unit feed the Nak amp, but that amp is blown. However the adapter will help me weasel out the signal & speaker leads in the factory harness so I can run an aftermarket amp in the trunk, which is where the factory amp is located?

In the end though I'd like to upgrade all the wiring at some point, but I can at least get the new stuff up and running.

Great help!

[RDM]

There's really no need to upgrade the speaker wiring unless you plan on running several hundred watts to each door. The OE twisted pair is 16gauge which is plenty large enough to handle the power. People often mistake speaker wiring with power wiring, you're not running the same amount of voltage, so the 'bigger is better' theory isn't true unless it's solid core wire. Stranded wire creates it's own resistance, and with minimal voltage (say the 3-5V a speaker receives) you won't gain anything by running new wire. Plus the OE shielded cable for the preamp signal is well isolated from interference, if you ran your own RCA cables you'd want to copy that routing to keep them away from any EMI. I'd use everything that already exists and be done with it.

[Ross W.]

I'd use everything that already exists and be done with it.

Good point. I'll take that into very serious consideration. I'll be running an amp that delivers 150w / channel so 16 awg wire is fine. Does anybody have a pin-out of the harness plugs at the amp end? That would be a great help!

[RDM]

Good point. I'll take that into very serious consideration. I'll be running an amp that delivers 150w / channel so 16 awg wire is fine. Does anybody have a pin-out of the harness plugs at the amp end? That would be a great help!

The signal input will match the wires you have in the dash, then the output wires are the same for any Toyota, you can find it in 12volt.com but I think they're like pink and purple, light green and blue, red and white, and yellow and black for the speakers. They're twisted together so it's easy to find if you strip back the loom a bit. You can even use the remote turn-on wire too at the radio so all you'll need to run is a power wire from the battery.

[1990LS400]

Attached is the 1994 LS400 Nakamichi diagram from the "Auto Repair Reference Center" (ARRC) website that is available through many public libraries.

1994 LS400 Nakamichi diagram.pdf

[Ross W.]

Awesome folks! I really appreciate the efforts and advice!

[Ross W.]

Okay, now here's where I'm going to push the limit: Is there a source for an unloaded connector that will plug into the amp end of the harness, so I can stab in my own adapter? I'd like to keep the original amp for future bargaining chips, otherwise I'd de-solder the input plug from the board and use it. I certainly don't want to cut up the original chassis harness!

[RDM]

Okay, now here's where I'm going to push the limit: Is there a source for an unloaded connector that will plug into the amp end of the harness, so I can stab in my own adapter? I'd like to keep the original amp for future bargaining chips, otherwise I'd de-solder the input plug from the board and use it. I certainly don't want to cut up the original chassis harness!

I highly doubt it, I've never seen one in all my years of car audio work. Your only option would be to find a matching plug somewhere else in the car (unlikely, but worth a shot), then cut it out of a salvage car. I did that for a customer on a Nissan Maxima, we found that the plug in the door matched something else that wasn't offered like an amp plug, so I cut one out of a wrecked car.

[Ross W.]

Your only option would be to find a matching plug somewhere else in the car.....so I cut one out of a wrecked car.

Thanks! Already considering that. I've been darkly muttering to myself that I need to scour the yards for goodies!

[Ross W.]

Thanks again folks for all your help.

One thing I can't find solid info on is where the factory amp is located? I ask 5 different techs and I get 5 different answers! One says under the front seat, another says in the trunk, etc.!!

[RDM]

Look under the seat and tell us where there's room for an amp.

It's in the trunk. Right side.

[Ross W.]

Look under the seat and tell us where there's room for an amp.

It's in the trunk. Right side.

Thanks! When a mechanic confidently told me under the right front seat..... well..... :chairshot:

I'm pulling the trunk panels anyway, both for wiring purposes and a general cleanup!