1995 LS400 - can't stop alarm!

[Bobfreeman]

Hi all,

My LS400 lives in a dry garage and comes out on sunny days but suddenly the alarm started sounding and won't turn off? I've replaced fob Battery and can get in, start the car, and drive away but still the alarm sounds? Only way to stop the noise is disconnect the Battery but, as soon as it is reconnected, away goes the alarm again....

Central locking works fine, engine starts - no other problems except this infernal noise!

Any thoughts before I send it away to become a washing machine?

Bob

[ambermarine]

Hi Bob

Take out the dome fuse and leave the car for 10 minutes then replace the fuse .

This usually resets the ecu for the transponder receiver ,if this does not work there is a fault with the reciever.

[Malc]

....  also maybe remove all metallic objects from inside the cabin area and pockets .............  that might help  ..  how old is the main Battery ? that sometimes causes all sorts of gremlins if it's past it's best too

I also found that some people's upgraded wifi signal upsets it sometimes ........  new neighbour might need re-educating !  hahahahaha

There's further historic posts on this forum about this infernal issue but doubt anyone has really got to the bottom of the reasons really.

I'll buy your, to be, washing machine if it really is the only problem  .....  used 20 year old washing machines you usually have to pay to have taken away but I won't charge ........  ..............heheheheheh

Good luck 

Malc

[Bobfreeman]

Thanks for these - good to know people are out there!

I have disconnected the Battery overnight (peace and quiet) but about 15 seconds after I reconnect it, the alarm goes off again. Everything is working, central locking/remote is fine and the car starts (if you can cope with the noise) - don't know where to find the dome fuse but I imagine disconnecting the Battery would have the same effect?

The damn alarm really is its only problem  - its been a grand car for the last three years and then this starts. At the moment its totally unusable and, if I can't find an answer its off to eBay

 

Bob

[lockeyboy]

Hi bob

my Honda Accord did the same recently

is there not a fuse solely for the alarm?

i had the Aa remove the fuse by haven't yet tried it back in yet so my central locking is also not working 

 

Would be a shame to get rid of it if you could just disable the alarm. 

[Malc]

..............  the fuse that disables the alarm on the Mk3 also disfunctions the steering column in-out movement  ...............  as your last resort I guess

Malc

[Bobfreeman]

Tried the fuse - it cuts all the interior lights, C/L and steering. Can't find the damn siren otherwise I'd do something drastic to its wires....

Don't want to ask a Lexus dealer, if I can help it, as just the diagnostics will cost the same as a small third world country's national debt....

By the way - Battery is a couple of years old but absolutely fine - the car is kept on a up market trickle charger, changed the fob Battery as well. It seems strange that I can start and drive it - albeit sounding like something from the California Highway Patrol - at least the immobiliser is okay....

Any one, with a large trailer, or ear plugs, want a cheap LS400 with a death wish?

 

Bob

[steve2006]

Alarm sounder should be located behind the driver's side wheel arch liner to the left of the wheel quite high up

[Bobfreeman]

Thanks Steve.

I know I'm being thick but how do I access it? Is it from underneath, inside the car or from inside the bonnet? I found something that looked like another horn in the engine bay, tucked up in the corner by the A post on the drivers side but the sound didn't seem to be coming from there

Bob

[Malc]

thought ..........  maybe find an independent alarm installer to remove yours

Malc

[steve2006]

14 hours ago, Bobfreeman said:

Thanks Steve.

I know I'm being thick but how do I access it? Is it from underneath, inside the car or from inside the bonnet? I found something that looked like another horn in the engine bay, tucked up in the corner by the A post on the drivers side but the sound didn't seem to be coming from there

Bob

You need to at least partially remove the front driver's side wheel arch liner, removing the wheel first will help. Liner is held in with screws and clips.

[steve2006]

Another thing to check is the bonnet lock alarm switch, lift the bonnet and then make sure the electrical connector on the lock is secure, also make sure the boot lock connections are good as all of these are connected to the alarm system. If the system thinks the boot or bonnet are open the alarm will sound.

[plexus914]

lexus-doc,ru

For 95 model: Look for BODY ELECTRICAL-THEFT DETERRENT SYSTEM and BODY ELECTRICAL-MULTIPLEX COMMUNICATION SYSTEM.

For 96 model: Look for BODY ELECTRICAL-THEFT DETERRENT SYSTEM.

 

[Bobfreeman]

Thanks All!

im going to have a crack at disconnecting the siren  Spent a fortune on it, over the years.

.

bob

[Malc]

Robert, I'd be really interested to know how you achieve this in reality, with all the " doing " pitfalls etc, as I'm sure others would here too.

Thanks

Malcolm

[Bobfreeman]

Hi Malc

Been told it lives under the offside wheel arch liner so,  if I can get to it, that's the second idea. The first is to call the AA and tell them I can't stop the alarm......

All other, useful, suggestions are gratefully received 

Bob

[runsgrateasanut]

Used to have alarm problems on my S320 and the forum was always very helpful but for obvious reasons they didn't like to advertise too often how to disable the Alarm system.  It used to require two specific cables to be spliced and reocnnected as I recall.

On the Lexus unless you know for certain that just snipping a cable won't prevent your starting system from operating I'd be somewhat cautious.  How about wrapping the siren in something to insulate the sound until you've discovered the reason for the fault? Just a thought.

[royzels]

Hello, I had the very same problem with my Mk 3 1995....I tried each and every way to stop it, but to no avail.... I eventually got the AA to take my car on a low loader  to the nearest Lexus Dealer, who stopped the  alarm sounding, and charged me £100............. Expensive I guess, but at least it stopped me going mad... Hope this helps..... Cheers Roy.

[steve2006]

20 hours ago, royzels said:

Hello, I had the very same problem with my Mk 3 1995....I tried each and every way to stop it, but to no avail.... I eventually got the AA to take my car on a low loader  to the nearest Lexus Dealer, who stopped the  alarm sounding, and charged me £100............. Expensive I guess, but at least it stopped me going mad... Hope this helps..... Cheers Roy.

£100.00.....mmmm Lexus dealers do know how to charge and no I don't know the part number for the required special tool shown below.

[runsgrateasanut]

If its a conventional Snail shaped horn a bit of plastic insert and then a squirt of gorilla filler should deaden the sound, until explored how to solve problem. Can then scrape out. Without responsibility or liability  as they say!

Gorilla filler had another use  for my older Mercedes to firm up the wallowy spring style front seats. 

[Bobfreeman]

Hi All

 

Bit of an update on this problem. I tried leaving the Battery disconnected for a couple of days and no joy at all. Left it disconnected for two weeks and the alarm appears to have reset and now works fine again. Don't trust it, of course, stand next to it, spanner in hand, ready to undo the Battery lead, but, at least, it's progress

 

Bob

[royzels]

Hello......Yes at least it progress....Lets hope it cures it.... Cheers Roy.

[steve2006]

Could be a good sign, IIRC the alarm system has a built in back up Battery so even if you disconnect the main car Battery the thing remains alive until the back up depletes. Given the time you left the Battery disconnected it will have fully discharged and then rebooted to its correct mode so no more false alarms hopefully.

Thanks for coming back with the update, all useful information.

[lockeyboy]

I think the problem is catching 

mine has recently been going off once a day and sometimes twice then everything seems fine again

its normally during the day and I suspect could be passing rumbling cars...

 

[Malc]

.......  is  this just a Mk3 problem then ??

Malc