edtbjon

Hi all!
Setup: '95 LS400 with a standard (Pioneer?) HU. (There is a "nowadays useless" Lexus GSM telephone installed, which I plan to rip out, but that's a later project.)
The headunit seems to be working fine at all times, as the display is showing radio channels, settings etc. When starting the stereo with the key in ACC all the speakers are working and the stereo sounds OK, but as soon as I start the engine, there is absolutely no sound from the speakers, even at full volume.
I have searched these forums and the 'net to no avail. Is there anyone who have encountered and solved this problem?

//Björn

onelove316

most likely you are clipping the amp when you start the car, the amp is suppose to kick off for a second when you start up the car, yours is prolly clipping when this happens, first this is to unhook positive and negitive battery and go into the car and press brake pedal, turn head light on then off this will clear all the power out of everything wait a few mins after you have done this, check all fuses to be sure you dont have any that are slightly burnt looking, now check positive and negitive wires for corrosion as this is something that will cause this to happen as well bad positive and negitives will do the same thing, mine did it for a while i changed out both positive and negitive terminals fixed it right up, now if they look good hook them up if theis still does not fix it you could have a amp thats on its last leg or the connection to the amp could be crap, so it might not be getting enough power but its a lexus i dought thats it, let me know how it goes, derrick

Kansas

Björn,

It is possible that the mute function of your "Lexus GSM telephone" is becoming grounded causing the radio speakers to mute. It is a fairly common problem on the U.S. specification LS400 with the dealer installed Lexus phone.

This problem can usually be resolved on on a U.S. specification LS400 by unplugging the telephone components from the car's wiring harness. Unplug the cable for the handset cradle -- you may have to remove the vent you see when the front arm rest is raised. Look for the telephone ECU in the trunk. It is probably under the removable floor on the left or right side of the trunk.

The Lexus audio and telephone systems in the European specification LS400 are quite different from those on U.S. models. On some Lexus phone systems in the U.S., after unplugging two large telephone connectors from the phone ECU in the trunk, it is necessary to plug them together to complete a circuit. One thing I remember is that it is not necessary to remove the telephone controller from the left side of the steering wheel.

There are threads somewhere on this forum that discuss this telephone issue but I would have difficulty finding them.

edtbjon

I've now tried to "null the computor" by disconnecting the battery as onelove316 suggested to no avail. Still the same result. But thank you anyhow, it was certainly worth a try. (... and easy too. )
I will get on to what Kansas suggests tomorrow. As I said above, I'm going to take out the phone too. (To paraphrase Brüno: "That phone is soo 1996.")
I will eventually install a new headunit (with one or two amplifiers) from scratch and some new speakers, but that is quite a major operation and as the stereo actually is working apart from the "catch22" that the engine have to be turned off. The LS is a very nice car, (I bought it yesterday ) but it's supposed to be driven.

Anyhow, thank you for the suggestions so far. Keep 'em coming.

//Björn

edtbjon

Well, the tip from Kansas seems to have resolved the problem. (I'm not sure yet, as when the car have been standing for a few hours, the stereo will work with the engine running for a little while, like a few minutes or so.) But anyhow, the phone ECU was on the right side of my trunk and it was very easy to disconnect the cable going to the ECU and then putting the two connectors together.

I got around of taking some pictures, so in my (european) car, the first pict is of where the phone ECU is located (i.e. on the right side of the trunk under the floor cover.
The second pict shows the ECU connectors disconnected. Now all you have to do is to connect the two connectors at the bottom of the second picture, which is what I've done in the third pict.

A final note: Yes, the stereo playing CDs actually sounds really decent for a '95 system. I almost regret ordering a $500 Alpine HU, but I recon that the sound will only get better. Luxury problems...

//Björn

PureDrifter

iTrader: (10)

good to know you got it fixed, thanks for posting up your resolution

adorjr

The head unit was working but only a little bit of sound coming from the speakers. The Search button directed me to this post and Kansas' directions on the phone ECU. I am mechanically challenged but disconnected the phone ECU connectors, and when I turned the ignition key, the sound of an old Nak stereo was music. Thank you so much.

edtbjon

One thing I found out after a while is that the speaker in the rear left door didn't work. As I'm in the process of rebuilding the whole sound system I removed the inner door panel to take out the speaker box. There was nothing wrong with the speaker as such, but there was nothing coming through the wires.
When I read the 1996-lexus-ls400-stereo-install-wiring-info-diagrams thread, I finally found out why the speaker didn't work. I.e. the left back speaker is used by the telephone system and the wires are routed from the amp to the booth where the phone HU is located and then up the left side to the rear door. Again, as I'm rebuilding the system from scratch I didn't have to find the specific location of the lost speaker signal, but I recon it get lost somewhere around where the old phone HU was located. (See above on my pictures.)
(What I done is to solder a good speaker wire after cutting the 2 wires by the connector in the door post and route that new pair or wires to the front where I will put my door speakers amplifier. If I'd wound have wanted the original setup to work I'd probably route the wires under the floor mat to the amplifier and splice it by the speaker connector.

//Björn