91 LS400 alarm going off randomly

[Earl!]

Hey guys,

I just recently bought a 91 LS400 and have noticed that the factory alarm goes off randomly. My keyless entry system doesn't work, so I'm wondering if that may have something to do with the alarm since keyless entry is generally included with an aftermarket alarm. The only other thing that I can think of that may be the cause of this is the cold weather. I know that sounds crazy but the times it went off randomly were below zero days, hmmm?? Any suggestions :?:

[UCF3]

If the keyless entry on the stock system doesn't work, that won't cause the factory alarm to randomly turn on. If you really have an aftermarket alarm on the car, that should be the culprit. When the alarm goes off, see whether if it's your headlights and horn only. If it's anything else, then you'll know that the after market alarm is the trouble. For the aftermarket alarm, generally you'll find an additional wire on the postive side of the battery. Just disconnect it and the alarm should stop. If it's the factory alarm, you might want to consider either disconnecting it permanently, or take it to Lexus and getting the entire alarm system replaced. They generally cost $300 to $500, but since you actually have a key with the door unlock/lock on it. Comes in handy.

[Earl!]

Thanks for the help UCF3, I'm going to check it out this afternoon.

[jrulmyr]

I have the same random alarm problem with the '90 LS400. It is the OEM version (just lights and horn). Did you get it turned OFF? How? Let me know how your resolved the issue - I just want to turn off this feature.