Radio Went On Mute

[qha_vn]

my radio suddenly went on mute mode yesterday (it worked normally just a few hours before). It does not produce any sound at all at any volume level, at any preset anf non preset radio station. the radio unit looks fine when i turn it on, all lights are lit, radio statiions display normally. the only thing is no sound at all

i tried to find a "mute" button but it seems not have any. any idea?

('90 ls400 with 90k on it)

[1990LS400]

One thing that can cause the radio to go mute is if the car has a defective phone system - even if the phone system is not being used. The radio on U.S. models automatically mutes when a phone call is in progress. The mute function on Lexus radios work on the same principle as on cars from most other manufacturers. When a phone call is in progress, the phone system grounds the mute wire going to the radio.

The problem could also be in the radio or amplifier. Your car could be different than those sold in the U.S. Does the VN = Viet Nam? The audio system in Asian market cars was quite different than those in U.S. cars.

[qha_vn]

thanks for the quick reply

so there might be an unexpected short in mute line? how can i test it?

my car doesnt have phone option. Also my car was imported from US so there would be no difference (yes VN stands for Vietnam)

[1990LS400]

In the few times I have heard about a defective phone system causing the radio to mute, the car did have the phone installed. All LS400's are fully prewired at the factory for a phone.

I don't know if it will help you any but attached is a wiring diagram for the 1990 LS400 audio system.

1990_LS400_audio_system.pdf

[qha_vn]

it suddenly works again tonight as if it was never silent before :o

potential future problem :(

[UCF3]

Gha Vn:

Do you have a Lexus phone? If you don't, it maybe a future problem that you'll have to troubleshoot.

[qha_vn]

no i dont have a lexus phone. by the way, dont know if i can have it set up, is that phone module normal GSM or need a special service from lexus?

[1990LS400]

None of the phones for the U.S. LS400 models (1990 - 2000) were GSM. As far as I know, all were analog but the ones in the late 1990s might have supported TDMA or CDMA - definitely not GSM.

It is fairly easy to install a phone kit in an LS if you don't mind doing a little minor disassembly of the interior - there are plenty of Bluetooth kits that interface with a modern GSM phone. Or you could use a Bluetooth headset or a visor mounted Bluetooth unit.

[qha_vn]

None of the phones for the U.S. LS400 models (1990 - 2000) were GSM. As far as I know, all were analog but the ones in the late 1990s might have supported TDMA or CDMA - definitely not GSM.

It is fairly easy to install a phone kit in an LS if you don't mind doing a little minor disassembly of the interior - there are plenty of Bluetooth kits that interface with a modern GSM phone. Or you could use a Bluetooth headset or a visor mounted Bluetooth unit.

so i cant use the OEM phone and the OEM wiring?

[1990LS400]

None of the phones for the U.S. LS400 models (1990 - 2000) were GSM. As far as I know, all were analog but the ones in the late 1990s might have supported TDMA or CDMA - definitely not GSM.

It is fairly easy to install a phone kit in an LS if you don't mind doing a little minor disassembly of the interior - there are plenty of Bluetooth kits that interface with a modern GSM phone. Or you could use a Bluetooth headset or a visor mounted Bluetooth unit.

so i cant use the OEM phone and the OEM wiring?

Correct. It is possible to connect an aftermarket phone kit to the OEM phone wire harness so that the call plays through the door speaker like on the dealer installed Lexus phone. Jainla did this on his LS430. Or you can do something like I did and use an external speaker and attach the aftermarket phone kit's mute wire to a mute pin on the OEM phone wire harness. I don't know where you would find a mute pin on a 1990 LS but it would likely be in the trunk.

Or you could connect an aftermarket phone kit's mute wire to a mute pin on the headunit or amp. The wiring diagram I posted earlier shows the wire color. Personally, I think it is more risky to mess with the headunit or amp and that it is safer to connect aftermarket phone kits to the car's built-in phone harness.

[qha_vn]

thanks a lot, it seems interesting having that feature. could you please recommend some after market kits that can be intergrated with OEM wiring harness.

i know the mute wire. just to be confirmed, is the sound system mute when i ground the mute wire?

[pishta]

In the few times I have heard about a defective phone system causing the radio to mute, the car did have the phone installed. All LS400's are fully prewired at the factory for a phone.

I don't know if it will help you any but attached is a wiring diagram for the 1990 LS400 audio system.

Could you splice an Ipod out into the pink/blue and violet/lt. green input of the head unit? Would that give you an "in" into the stock amp?

[white ls400]

ok sorry to bother yall but im having this mute problem and i do have a phone installed.What should i do to correct this... I know that this phone is a aftermarket option and not a lexus one should i just snip the wires and see if it works or would it be easier removing the mute wire in the head unit

[1990LS400]

ok sorry to bother yall but im having this mute problem and i do have a phone installed.What should i do to correct this... I know that this phone is a aftermarket option and not a lexus one should i just snip the wires and see if it works or would it be easier removing the mute wire in the head unit

IMO, the lack of sound from your radio is more likely a defect in your amp or head unit than with the mute connection from your phone. But if you want to remove your phone, it is better to unplug phone components rather than to cut wires. Was it on this forum or Clublexus where someone reported in the past few days that he cut the wires from his phone cradle and then had all sorts of other electrical problems? - he must have grounded a hot wire and blown a fuse when he cut the wires.

I'm not clear on whether your phone is a Lexus phone or an aftermarket kit. If it is a Lexus phone, one of us might be able to tell how to unplug the various components. If it is an aftermarket phone kit, you would have to trace the wires from the phone kit to whereever they connect on the car's electrical system.

What year is your LS? It helps others help you if you would put the year of the car in your signature or in with the model designation (e.g. 19xx LS400) that shows on the left side of a thread.

[white ls400]

Its a 90 model ls... It ended up being that mute wire... I pulled the blue socket out of the back of the cd player that contains the mute wire and the radio started working again... minus the subwoofer... So im gunna snip the wire but im not sure which red/white wire it is considering there's two... can anyone shed any light

[1990LS400]

Its a 90 model ls... It ended up being that mute wire... I pulled the blue socket out of the back of the cd player that contains the mute wire and the radio started working again... minus the subwoofer... So im gunna snip the wire but im not sure which red/white wire it is considering there's two... can anyone shed any light

Seems a little odd ... I don't see a mute wire at the CD changer on the audio system wiring diagram for a 90 LS that I posted earlier in this thread. Generally the mute wire is labeled "MUTE", "TMUT" or something similar.

Are you saying that the mute wire from your phone kit is attached to a wire leading in to your CD player? If so, what color wire is it?