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Does anyone know where the alarm siren location is for a 2000 LS400, my alarm keeps going off randomly, I've read the radar under the centre console can trigger if metallic objects are in the arm rest, I've removed literally everything and it still goes off, I even turned down the knob 'minus' as far as it goes and even removed it and it still went off by itself. So my next step is to just disconnect the sirens, any help much appreciated.

Hi again everyone. Hope you had a good Christmas and that the new year is good, too. I have an issue with the (auxillary) 12 volt battery going flat when the car is standing. It's a nearly new battery, bit I am aware that a new battery can be faulty. I have fitted a battery isolator switch for when the car is left standing, which resolves things (in a rather unsatisfactory way!). I detect no parasitic drain on the battery when the car is resting. I haven't tested it yet with the alarm turned on, though... Which might be tricky to do, but I'm probably going to have to give it a bash. What I have measured is the voltage of the battery (12.5v), then left the car for a day with the battery connected and the alarm on, and measured it again... 12.25v. both measurements taken with the battery disconnected. According to a handy table I've found, this represents an estimated reduction in charge state from 90% to 50% in just 24 hours😵. Given that it's a 45Ah battery this is equivalent to a 750mA drain, assuming my calculations are correct. My hunch is a problematic alarm or a knackered battery. I will see if I can establish drain again tomorrow, but with the alarm enabled. Any other car, I would have fitted a more macho battery, but Lexus haven't provided enough space for one (on the basis that we don't need cranking amps on a hybrid). Any advice welcome.

Hi all, I have had my CT now for two months and tonight the alarm has gone off twice for no reason. Checked my security camera and no cars or people have gone past to set the alarm off. Car has been parked up since 15:00 today and the alarm has gone off at 20:32 and 22:03 (time checked on camera) weather is fine no strong wind or rain, I’m not near anything that involves strong vibrations. has anyone experienced there alarm going off randomly? Just puzzled why this has happened. regards Joel

Has anybody had the seat belt warning alarm sound when driving? I don't mean because you did not plug in before setting off. I don’t think the false alarm is a collision sensor fault – it is the seat belt alarm – I tested this. I took everything off the seats and the alarm still kept going off intermittently. This was annoying when on a motorway. I stopped and plugged in all the seatbelts and the alarm stopped. I drove around for some time with all the belts plugged in. I asked the dealer to investigate at a service (may have been last November). The guys did not find any problems – however, the alarm stopped so I think they tinkered a bit – great outcome but no RCA. That is until two days ago – the seat belt alarm went off and stopped (after a few mins) a few more times. So the belts are all plugged in again and the alarm is quiet. Anyone have any ideas?

Hi guys, my SC has been laid up for 4 weeks now so checked it this morning and found it wouldn't remote unlock so the battery is prob flat... doh! Before I unlock the door manually and set off the alarm, assuming it's still operating, how can I quickly disarm it once it starts? Key into the ignition? Or maybe wait till 8pm tonight so everyone thinks it's for the NHS??? LOL Thx :)

Blissfully watching TV last night when I heard a car alarm activating. Extremely loud and very close. Suddenly realised it was my RX in the car port. Every light seemed to be flashing and it was like the end of the world. Managed to switch it off using the remote. Locked the car again and no further issue. Recently the neighbours at the bottom of our garden have acquired a cat who is adept at climbing on the roof of our bungalow and my wife has seen him on top of the car port and the 6 foot high wall that encloses it. Would a jumping cat be enough to trigger the alarm? The car port is totally enclosed with locked 6 foot high gates so an intruder of humankind is unlikely. Anyone got any ideas please?

Hello The ear-splitting factory alarm on my 1998 LS400 has been going off inappropriately for a few months now. This usually happen just as I lock it, but not exclusively, or when I switch the engine off. It does not immobilise the vehicle (can be driven with the alarm still sounding) and can only be stopped by unplugging the battery. So far I have dialled down the proximity sensor underneath the centre armrest and changed the batteries in the fobs. Since the alarm doesn't have any noticeable effect other than deafening me, my next move will probably be to find the siren and unplug it. I don't think the vehicle battery is the problem as it's relatively new and doesn't have any issues. Any advice would be much appreciated. Thanks

So for the last few month I have been having problems with my 99' Lexus IS200. It seems that there was a problem with the alarm that has been setting is off at all hours of the morning. The only way I found around it was to leave my car unlocked over night, which wasn't very comforting. So I was reading around the forums for a fix but I couldn't find a clear solution for it. I found that it may be the motion sensor that was causing the problem but I couldn't find out if it could be disabled or how to disable it, so I went hunting. I decided that I would remove the roof lining and heat shrink all the wires as this may have been the problem. After pulling my entire roof apart I found that the motion sensor itself was inside the dome light and that it was as simple as unscrewing 3 screws and disconnecting a single harness. So if you are having the same problem try disconnecting it before you go ahead and waste a lot of time haha. I have only just disconnected the sensor so I'm not 100% sure if it is the problem but I'm certain that it is. I will post back in a few days telling you how I go. Disable motion sensor Time: 5 minutes Difficulty: Easy Motion sensor harness: The big circle is the motion sensor. The small circle is the harness to disconnect. Removing roof lining Time: 40 minutes Difficulty: Intermediate 1. Remove the A-pillar by gently pulling. 2. Remove the B-pillar by removing the seat belt cover, unbolt the 14mm seat belt bolt and gently pull the cover off. 3. Remove the C-pillar the same as the A-pillar. 4. Remove the map light by pulling down or prying it. 5. Remove dome light by removing the lens cover and unscrewing the 3 screws. 6. Remove rear-view mirror by prying the cover and removing the 2 screws. 7. Remove the sun visors by removing the 2 screws on the outer side, disconnect the harness and remove the screw holding the pivot point. 8. Remove the grab handles by removing the covers on the end of the handles and unbolt the 2 bolts on either end. 9. Remove the 2 push in clips near the rear window(sorry no pictures) 10. Remove the roof lining. The roof lining should now be completely free. The easiest way I found to get it out is by folding down the passengers seat and removing the liner through the rear passengers door. I hope this helps anyone who is having the same problem as me. If you have an questions feel free to post of pm me. If anyone is curious I may weigh some of the part for those wondering about weight stripping If you would like to see more photos click the link below: http://s839.photobucket.com/user/Matt_Shipman/library/Lexus%20IS200%20roof%20lining%20and%20alarm%20problem

Sorry to bother you with another RX300 alarm issue. I have checked previous threads and tried some of the suggested fixes but without success. A few weeks ago the alarm started sounding at random when the car was in a locked status. It usually happened up to 10-40 minutes after I had locked the car. Everything else seems to be working. I installed new batteries in the two remotes and grey sub key = no difference. I have a temporary fix by retaining one black key in the ignition and manually locking the driver's door with the other. Hardy satisfactory but it works. Any tips or suggestions would be welcome. Thanks - Chris

Hi my 200is remote locking and alarm activation suddenly stoped working. Press the lock or unlock and nothing happens, not even indicator lights flash. Central locking working from main switch but not from door lock with key. The car starts no problem. What I have done is replace battery in both keys. Both the light on key flashing bright. Tryed recoding key with 5 lock method. It gose threw the complete sequence but still nothing. Checked all 3 fuse boxes. Any advice as to what I can check or try or possible problem.

Good evening all, my first post (but not my first visit) to this fine forum. I have recently bought myself an '03 IS200 Sport and am loving it....however, after a couple of weeks of no faults, Saturday the alarm started sounding about 15 seconds after I lock the car with the key fob and has done it since. I searched around on the forum and found that this could be caused by a number of things, one of which is due to low battery voltage. This leads me to speculate that my battery is slightly discharged. long story short, I've put footwell lights in and have been doing other minor modifications to the interior and have been leaving my door open for several hours at a time , I really should know better! Also, this morning I noticed my alternator fuse had been blown by the previous and they had bodge it back together with a picture hook! I replaced the fuse today after my internal electrics went dead but everything on the constant 12V feed was working. Everything is back to usual and I assumed that the battery would charge back up to its previous level on my way home from work, about a half hour drive. When I got home I reluctantly locked the car with the fob and about a minute later the alarm went off. I have also read that there could be a fault with the internal motion sensor in the dome light but, as I said, the alarm only started going off on Saturday and hadn't given me any trouble which leads me to my first theory. Basically, is there anything else that could be causing my alarm to go off when I lock the car? I checked the voltage and current draw on the (new) battery and it's all normal so could it just need a quick top up of juice? Sorry for the length of this novel! Any help or insight into this would be greatly appreciated :) Thanks J

My Lexus SC430 parking sensor alarm sounds intermittently while I am driving. (No, I do not tailgate the car in front.) It has happened several times, all but once when it was raining. On that one occasion, the sun was shining. It happened again today while it was raining, and continued to sound after the rain had stopped, but the road was still wet. What could be causing this to happen, and how can it be prevented, please? I have decided to fit an ON-OFF switch, if the problem cannot be solved conventionally.

Hi, My first post as a new member, so hope this isn't too long winded... I have a '97 LS400, but only one key. The dealership seems to be able to supply a chipped spare key, but that won't activate/deactivate the factory fitted locking and alarm, for which I have a separate key fob (lock, unlock, boot release and panic buttons). They claim they are no longer available from Lexus. So.. is there a 3rd party key fob that I can buy and arrange to be programmed? The dealership says that if I buy a spare key it will unlock and start the car, but I will have to tolerate 30 seconds of the alarm going off (which is clearly unacceptable). Advice welcome

Hi All, New to the forum. I have an RX300 where the security light does not flash when the doors are locked. When I bought the car the OSR door did not lock and assumed this was the reason the light did not flash. I have the door lock fixed but no change. Any ideas would be greatly appreciated.

Hi there, I have a 1996 300 sport, does anyone know how I can dissable the alarm as it keeps randomly going off?

Today my 2001 IS200 SE threw an electrical fit and I wondered if anyone else has experienced this. Symptoms are as follows: Alarm wont deactivate from Fob, repeatedly initiating and resetting on opening door, boot, bonnet or engine start (engine starts and runs as normal). Hazards don't flash when alarm sounds. Fuel gauge operates intermittently while low fuel light flashes (tank is 3/4 full). Battery discharge warning light comes on intermittently (New Battery fitted). Immediate MPG & Engine Temp gauge inactive. Outside temp gauge shows "E". This all started today at the same time. Car is booked in for a diagnostics tomo morning, but in meantime any ideas?

Ok, so here is my problem. I have a lovely 1997 GS300 which has recently developed a very annoying alarm problem. Symptoms are as follows... 1. Use key fob to unlock car, lights flash twice to indicate alarm is off and doors unlocked, no problem. 2. Put key in ignition and the steering wheel comes out, no problem. 3. Turn on the ignition, alarm continuously sounds. Trying to turn it off with the key fob doesn't work. 4. Start the engine, alarm changes from continuous to intermittent . 5. Drive away down the road, with alarm sounding and getting some very dodgy looks. 6. After about 2-4 minutes the alarm starts to sound a bit pathetic and then eventually stops. 7. Can now drive around all day with no problems unless I stop and turn off the engine in which case there is a high probability that we are right back to symptom 1 again! I did disconnect the battery for a couple of days in the hope that this would reset the alarm, but to no avail. So, any ideas? Thanks in advance.