93 Ls 400 Built In Telephone Option

[TexLex2009]

I just bought m first Lexus ever and I am really happy with it. It is a 1993 with 210,000 miles on it. It has the usual issues, blacked out lcd on the climate control and clock, speedometer and tachometer needles that work intermittenly. The cd player gives an err message when I tried it. Nothing major.

I wanted to know if there is any way to use the built in mobile phone wiring with a current cell phone. Thanks for an awesome forum.

[1990LS400]

Similar questions about the phone and/or its wiring have been asked many (Oh, so many) times in the six years I've been on this forum.

The answer is "maybe". The 95-00 LS400 has a mute pin in a connector on the driver's side under the vent you see when you raise the armrest. The mute pin can be used with any modern phone kit, including Bluetooth phone kits, to automatically mute the audio system when a phone call is in progress. If I didn't have my phone kit connected to this mute pin, I'd probably never hear my phone ring while listening to loud music. In fact, I missed a lot of incoming calls before I connected my phone kit to the mute pin. My kit was on "auto answer" and my wife got tired of listening to the music when she called and I didn't hear the phone ring.

I don't know if anyone has ever looked to see if a similar mute pin in a 93-94 LS400. I know there wasn't a mute pin under the armrest in the 90 LS I had for (too) many years but there was a major redesign of the phone system for the 93 LS. 1993 was the first model year that a portable take-it-with-you handset was available in the LS.

The connector in the 95-97 LS that has the mute pin has a total of three pins if I remember correctly. (Blake, if you see this please correct me.) Which is the mute pin can be determined by probing the connector pins with an unpowered grounded test light (or just a plain grounded wire) while the radio is playing. When the mute pin is touched, the radio will mute.

If there is no mute pin under the armrest, there is a mute connection somewhere else -- on the telephone harness in the trunk or on the audio amplifier or headunit. The good thing about going after a mute connection on the telephone harness is that there is little chance of damaging the audio system when probing.

It is likely that pins on the telephone harness in the trunk could be used to play the audio from a phone kit through the rear left speaker -- Jainla did this on his 01 LS430 but I don't remember anyone trying on an LS400. All the LS400 phone kit installs I've seen have used small external speakers hidden under the dash. Also, there may be a coax cable under your center armrest that could be used with a phone charging cradle that has an antenna connection. If your car doesn't have a Lexus phone and the location of the other end of the coax isn't obvious, look above the headliner at the center of the rear window.

There are likely other parts of the OEM phone harness that could be used with an aftermarket kit but why bother. And there is nothing available to adapt the steering wheel phone control on an LS400 for an aftermarket phone kit -- trust me, looking for one almost became a career.

There are people on this forum -- Jainla, Blake918, me, and probably others -- who will attempt to answer your questions.

[blake918]

The connector in the 95-97 LS that has the mute pin has a total of three pins if I remember correctly. (Blake, if you see this please correct me.) Which is the mute pin can be determined by probing the connector pins with an unpowered grounded test light (or just a plain grounded wire) while the radio is playing. When the mute pin is touched, the radio will mute.

Like I need to correct the master! ;)

There are likely other parts of the OEM phone harness that could be used with an aftermarket kit but why bother. And there is nothing available to adapt the steering wheel phone control on an LS400 for an aftermarket phone kit -- trust me, looking for one almost became a career.

Quoted for truth. Get a Parrot or Motorola kit and forget about the Lexus system. I'd remove the transceiver before it dies and locks your a/c fan in on low speed.

[stroker]

Please tell me more about the transciever and how it affects the A/C fan when it dies, or does it not apply to my 91 LS 400?? Thanks, Bob

The connector in the 95-97 LS that has the mute pin has a total of three pins if I remember correctly. (Blake, if you see this please correct me.) Which is the mute pin can be determined by probing the connector pins with an unpowered grounded test light (or just a plain grounded wire) while the radio is playing. When the mute pin is touched, the radio will mute.

Like I need to correct the master! ;)

There are likely other parts of the OEM phone harness that could be used with an aftermarket kit but why bother. And there is nothing available to adapt the steering wheel phone control on an LS400 for an aftermarket phone kit -- trust me, looking for one almost became a career.

Quoted for truth. Get a Parrot or Motorola kit and forget about the Lexus system. I'd remove the transceiver before it dies and locks your a/c fan in on low speed.

[1990LS400]

Please tell me more about the transciever and how it affects the A/C fan when it dies, or does it not apply to my 91 LS 400?? Thanks, Bob

What Blake was referring to was that the HVAC fan speed can get "stuck" on low if the phone ECU or a related component fails. On the dealer installed Lexus phone systems, the HVAC fan speed automatically went to low when a phone call was in progress.

[TexLex2009]

Please tell me more about the transciever and how it affects the A/C fan when it dies, or does it not apply to my 91 LS 400?? Thanks, Bob

What Blake was referring to was that the HVAC fan speed can get "stuck" on low if the phone ECU or a related component fails. On the dealer installed Lexus phone systems, the HVAC fan speed automatically went to low when a phone call was in progress.

Thanks to you all. I am now on the hunt for a Parrot (Kit).