LS400 sound system problems

Lien · May 20, 2022

Need some advise on my new to me Ls 400 1993 sound system.

A few problems radio difficult to find station, cassette player doesn't work, cd changer plays but only sound on drivers side speakers , nothing from bass rear speaker. I put a multi meter on it recorded 6.5 v. Passenger speakers sounds like you are listening to music underwater.

Can these units be repaired or am I best to swop it out. If so what have people fitted?

Also clock /climate LCD displays unreadable.

Howplum · May 21, 2022

To take the last point first, I read somewhere that the LCD displays might be repairable/replaceable, but a used unit might work, although that would also be about 29 years old. It worked for me on my 1996.

As to your other problems, there is obviously an issue with the head unit, but maybe the amplifier is faulty as well. Apparently its in the boot behind the lining panel hiding the petrol tank.

I didn't have your issues, but ended up installing a modern double din unit with touchscreen, USB and AUX inputs. I had to buy the adaptor from the US, but for your year they seem to be available here. I did have to make a wiring adaptor, which involved a fair bit of research, but it was worth it in the end. It's connected to the existing amplifier and the sound is very good. The downside is that I can no longer use the CD player and there is no cassette player.

The AUX and USB sockets are to the left of the steering wheel in the picture.

Lien · May 22, 2022

Thanks for your reply.

I did locate the amp in the boot as you said. Is there a second one for the CD?

Your install looks very good!

Is there not anyway you can link to the CD unit in the boot.

Does your system still use the existing subwoofer?

Howplum · May 22, 2022

As far as I'm aware there is only one amplifier, although I'm no expert. The CD player was connected directly to the head unit. My amplifier drives all the speakers, including the sub woofer in the rear parcel shelf.

If you could get hold of a wiring diagram for your year that should help with your investigations, although I found a couple of US forums quite useful as well.

I guess at this point you might need to decide whether you want originality or something more up to date.

My unit is a Pioneer, with plenty of bells and whistles, which I got through eBay, so wasn't expensive. The main factor was the time it took for me figure out how to make the adaptor, since there didn't seem to be an off the shelf solution for my year.

steve2006 · May 22, 2022

On the 1993 model the amplifier is integrated into the head unit, there is no amplifier under the passenger seat or boot where the CD unit lives.

Getting hold of a known good used system is going to very difficult as mentioned by Howard and there is no “plug and play” option either for replacements.

I ended up hardwiring a JVC CD radio into mine using a single DIN conversion bracket and fitted a sub amplifier in the boot where the original 6 disc changer was using the aux out from the head unit.

Be aware that the OEM sub speaker is rated at 2 Ohms so the amp needs to match.

As for the LCD climate control I again replaced mine with a new display from a US supplier but it must be the RHD version ( which of course costs more!)

Both are not jobs for the faint hearted, even as a qualified electronics technician with wiring diagrams the sound system conversion took 2 days and the LCD replacement a couple of hours but both were still working fine 12 years later when I sold the car.

Howplum · May 22, 2022

Maybe this previous topic might help:

Lien · May 23, 2022

Thanks for feedback

Lien · June 6, 2022

I have done a little more investigation had a look at the speaker cones all seem to be good. Took the amp out in the boot for the sub had a look inside, circuit board looks ok nothing obvious .

So I suspect its the head unit as the both speakers on the passenger side are making sounds just very muffled nothing from sub. Would probably like to keep it stock .

Anyone recommend someone who repairs or have a second hand unit.

steve2006 · June 10, 2022

Probably NLA but here’s the price of the head unit !

As I mentioned you will be very lucky to find a good used replacement, maybe Yahoo Japan but once you have the cost plus agent fees and shipping it won’t be cheap.

I didn’t even repair my unit which was the Premium Sound System as I had no service manual or circuit diagram.

Finding a repairer will also prove difficult I think.

An easy way to test your speakers is to disconnect them one at a time then connect another known good speaker to the removed wires ( one off your home hi-fi will do) and then see if the sound is correct.

bazgtr · June 10, 2022

You can just remove the unit and put in a double din unit Dab radio which sometimes comes with dvd players etc. I did this to my previous one years ago.

Lien · June 13, 2022

I managed to check the speakers on the passenger side and they are all good.

So back to the head unit with cost like that its going to have to be a replacement.

Where did you buy the harness and plate to fit?

Thanks

Howplum · June 13, 2022

SeeThis adaptor looks like it is supposed to fit:

https://www.ebay.co.uk/itm/255313111468?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=pYNThPYtRZK&sssrc=2349624&ssuid=bPQ54hZdSAe&var=&widget_ver=artemis&media=COPY

As to the wiring harness adaptor, you may have to design your own, as I did, but that probably depends on the chosen head unit. My car is 1996 and I may still have my notes. Hopefully the wiring may be similar.

This link, although US based, might help:

https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/688594-1993-ls400-trying-to-wire-my-double-din.html

Lien · June 15, 2022

Hi Howard

That's great !

Appreciate the help, I will let you know what I do.

Lien · July 14, 2022

Well I went down the route of buying an original unit on eebay.

Unfortunately there was also a problem with the unit, in fact, more problems than mine!

So think its going to be aftermarket, if I can figure out the wiring to adapt the harness.

steve2006 · July 16, 2022

With no suitable “plug and play” adaptor available I hardwired a JVC single DIN CD/Tuner head unit in mine having identified all the speaker and power wires.

I removed the redundant CD changer in the boot and fitted a sub amp in its place then ran a screened cable from the head unit aux output to the sub amp.

I think it was 50W RMS per channel and a 100W RMS sub amplifier.

This retained the sub woofer feature and gave a nice sound.