Since there was a member hear asking about the muted sound from his LS400 Gen 1 sound system and how the phone had something to do with that. I did the search for phone removal.
All I ever find is more people saying to the questioneee is to search. There is nothing about removing the phone and what is required to eliminate the system from being muted. Even with google. I also have a question that can not be answered by anyone. Where can we get service information on the sound system? Schematics and that sort of thing.

And geee everytime anyone asks a question don't answer it just say search. With no answers there will be nothing to search for.

 

https://techinfo.toyota.com/techInfo...oyota.com%252F

If I'm not mistaken you should be able to access any schematics and other information through TIS. It costs $15 for two days but that's usually enough time to download every PDF available for your car. I've used this for my 2000 and I've used MINI's TIS for troubleshooting those.

 

I've been on this forum since around 2003 and don't remember a thread that has detailed instructions on how to remove a dealer installed Lexus brand phone from a gen 1 LS400. I've posted instructions without photos on how to do it on the 95-00 LS400 but the gen 1 is different.

It is really only a matter of unplugging all the phone components without cutting any wires. I think the phone ECU for the gen 1 LS400 is behind the trim panel on the left side of the trunk. Find the phone ECU and unplug the connectors from it. If there are two connectors that plug together like in the 95-00 LS400 then plug them together to complete a circuit.

You'll have to remove the console box insert to remove the phone handset cradle. If I remember correctly, there on one or two hidden screws at the bottom of the console box insert that have to be removed. Regardless, it is very easy to remove the console box insert. Do as much disassembly of the console as necessary to unplug the phone cradle from the connectors to the rear of the console box.

I don't remember anyone finding it necessary to remove the controller from the steering wheel. I doubt if a plastic blank is still available to fill in the hole after it is removed unless one can be obtained from a salvaged car.

The permanent mute of the audio system by the phone system is usually caused by the phone ECU "shorting out". One of the connectors to the phone ECU in the trunk contains an audio system mute pin.

What year LS400 do you have and which audio system? I may have a diagram I can post.

 

Kansas is right. The phone ECU is behind the panel where the tool tray is. Remove what looks like a printer cable. That is it. I went into the console and unplugged the phone board from the connector under the base of the console and mine started working. Don't know which one did it though.

 

Not on the early gen 1's, they are usually mounted biased to the left side in the top of the trunk.
I don't think they got fancy with the location till 92 or 93. I've seen more than 1 car with the transceiver where I said. Also not all had the steering wheel control either.
So there is a board under the console box?

 

Mine had one. They pulled the phone out and unplugged it from that board and left it exposed. I had to go under the liner to see where it was plugged in. Found it as well and unplugged it. I guess I should have taken pictures.

 

Hello Kansas. Thanks for all your help here. I recently purchased a 96 ls400 where my radio is muted and HVAC is not blowing enough. I feel it's related to the phone. I checked the trunk and it seems like the phone ECU has been removed. I don't see the harness with the white connectors too. I only see one cable that probably connects to the antenna maybe.
Now I want to check if removing the handset cradle would help. Can you please point me to your post with instructions for the 95-00 ls400? Thank you.

 

My memory of this phone stuff has faded some since it's been almost 7 years since I sold my 2000 LS400. I was able to find only one of my past posts that has a photo of the handset connector at the back of the center console under the upward facing air vent that is exposed when the arm rest is raised. The photo is for the 2000 LS400 but I think the 95-97 is similar. It's in the 2nd post in the following thread: https://www.clublexus.com/forums/ls-...5-success.html

Other posts in the thread may contain useful information. The format of the phone connectors under the back of the console in the 95-97 LS400 are a little different than those in the 98-00 LS400 but connectors in both have mute pins. I don't know if there is pin in one of the connectors that lowers the HVAC fan speed but maybe there is.

You might be able to unplug the phone handset after removing the little black vent cover and pulling out the short section of duct - possible in the 98-00 but I don't know about the 95-97. What you have to unplug depends on which of the two optional phone systems your 96 LS has. To remove the handset from the upper console tray it is necessary to pry out the black plastic tray insert. Pry around the insert with a trim removal tool or maybe a narrow blade putty knife and gradually free the insert from the upper console tray. Be careful not to break the insert since they have never been sold as a separate part.

If you don't see the white connectors in the trunk, whoever removed the phone ECU may have hidden them behind the trim panel. When the car comes out of the factory, the two large white connectors are plugged together through a plastic bracket on the bottom of the tool kit receptacle.

 

Thank you so much Jim (aka Kansas). I really appreciate you taking time to reply to my post. I checked the trunk and opened up the carpet and I don't see any harnesses tucked under.
Then I moved to the center console. I removed the wooden center cover and the cupholder. But I am not sure how to proceed. I am not sure how to remove the center console glove box. I did remove one screw up at the back of the console box. Any ideas how to proceed from here. Your input is very valuable.

I am actually wondering now if my car even came with a phone installed. I started this path because the issue is very similar. Radio comes on, but no sound. And HVAC even with highest setting is not blowing air fast enough. It could very well be some other issue that I am not looking into. Could it be the amplifier? If so how to check that.

I checked both the radio 1 and radio 2 fuses and they look good. Even replaced it with spare ones just to make sure and it works.
I am not sure what the issue is.

Please note that the dealer who sold me this car few days ago claims that the CD player was playing music. When I went to see the car he had to jump start the car. Not sure if I can take the word of the dealer though. These are the knowledge I have off of the car's history so far.

 

Does your upper console tray have a phone handset cradle or not? Even if your car had a phone system, I may not have been a dealer installed Lexus branded phone. If it wasn't a Lexus phone, then there may be nothing plugged into the connectors under the vent at the back of the center console.

The black HVAC vent that you see when the armrest is raised just snaps into place. It was very easy to pop out on my 2000 LS400. After removing this little vent on my 2000 LS400, there was a short length of HVAC ductwork that could be easily pulled up and out so that the phone connectors were easier to see. At least that's what I remember ... been a long time!

It's not necessary to remove the console wood or the cupholders to remove an OEM phone system. Removing an aftermarket phone system could be different. I installed several aftermarket phone systems in the old days and I crammed the components into whatever hidden spaces that were convenient.

Corrosion in the factory installed phone system wiring can also cause the radio to mute regardless of whether or not a Lexus phone was ever installed. Corrosion can cause the mute circuit to ground out which why it is important to ensure that the large white phone connectors in the trunk stay dry. I remember one thread about these phone connectors getting wet, corroding and the wires disintegrating causing grounding.

Maybe you could compare your 96 LS400 with another 95-97 LS400 to see if there is a difference in the amount of air moved by the blower fan. The heater/defroster in my 2000 LS400 was pathetically weak. It was frustrating to have to frequently pull off the road on winter trips to knock ice off the wipers. I was so pissed about it that I made sure that my next vehicle had heated wipers.

 

Thanks Kansas. The console didn't have any phone or a phone cradle that I can notice. So maybe it didn't come with a phone at all? It's possible.

When the phone is active, does the HVAC fan speed go to complete zero or does it blow slow? Because at full fan speed I could feel air on my hand. It's not the powerful I have seen. Maybe half of what I am used to from other cars. Good idea to check with another ls400 from the same generation. Good luck to me finding that.

​​​Maybe I should look at this issue at another angle. I am going to look into the amplifier next. Could it possibly be that? How do I check if the amplifier is good or not. Any other troubleshooting techniq techniques? Does the amp have its own fuse that I could check?

 

IIRC, there are two fuses for the audio system - Radio 1 and Radio 2. Your owners manual or diagrams on the fuse box lids will tell you where they are.

Again, IIRC, a call in progress on an LS400 Lexus brand phone system lowers the fan speed to a pretty low level. When the phone system mute circuit is grounded, it should still be possible to hear the radio audio but the level will be very low. I remember when I helped a friend remove the phone system from his 99 LS that we could hear is radio playing at a low volume before we disconnected the phone ECU after which the radio sprang to life. If you can't hear your radio at all, then it probably isn't a mute circuit problem.

Like I said, the heater/defroster in my 2000 LS400 pretty much sucked and could not produce enough air flow or heat to keep the windshield clear on very cold days - especially when it was snowing hard. The air conditioner was excellent though.

If your radio or amp needs repairing, maybe Factory Radio Service in California can help you: http://factoryradioservices.com/

Factory Radio Service repaired some issues with the Nakamichi in my 00 LS at the same time they installed an aux-in. Service was excellent and turnaround was quick.

 

Thank you Kansas. I checked both the fuses and both are good. I even replaced them with the spare ones (20A and 7.5A) and still was good.

My radio is completely muted. No sound from the speaker whatsoever. So I am thinking it's not the phone connection doing it, like you mentioned. That is a very valuable information. I hope it's just a bad amplifier and so I can then replace it and be done with it. I guess I don't know how to check if it's a bad amplifier or not.

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Well the easiest way to see if your amp is defective is to plug in another amp from a donor car. That's what we did to determine that my friend's 99 LS amp was OK. I removed the amp from my 2000 LS400, laid in on the floor behind the passenger seat in his 99 LS and plugged the cables from his amp into my amp. We didn't have to remove his amp to do this test.