myLEXsc400

I have had my 96 SC400 for the last 6 years, and the factory alarm has never given me issues....until recently. About a month ago it randomly started going off in the middle of the night, around 3-5 am, multiple times. Each time it would wake me up, i would unlock and lock it with the factory keyless entry, and i would turn off. Then about a half hour later, it would do it again, and again about a half hour later.

This is seriously affecting my sleep, and I'm sure my neighbors are trying to kill me over this. My car is parked outside, and every time it would go off, there was no one touching it or around it. It has happened in the middle of the night today again, went off on 3 or 4 separate occasions for no reason at all. Did anyone else experience this? What could it be, and how do i fix it?

This does not happen during the day

kizzle

Is your car lowered?

I would check the wirings under the driver fender side if you haven't relocated the wiring.

My car alarm used to go off in the middle of the night cause all my wires were chewed up from the tires.

myLEXsc400

interesting. yes, my car is lowered, but nowhere near low enought to chew through wiring, since it doesnt rub. but i will check

myLEXsc400

so anything else i should pay attention to?

TheAzn

iTrader: (2)

I have had this happen to me twice in the year and some months I've owned it. I haven't found the issue. Mine has went off once at a gas station when I locked it to go inside the store and once while I was at my shop.

Speculation for myself is either the clutch pedal/ neutral safety switch or my hood latch. My clutch pedal would not always spring all the way up, I would have to use my foot to nudge it fully up. Maybe it moves by itself during the times my car was locked and sounded the alarm. Or my hood latch as my CF hood just sits on the latch (hood not able to catch the lock). The hood latch does have an alarm switch in it.

andy2o3

Same thing happened to me. Found that the wiring in the trunk became frayed and the wires started arcing. screwing up my whole care electronics. I would definitely verify your wiring and ground.

myLEXsc400

yes, i definitely need to trace my wires, because it did it this weekend again. is there a fuse that you can pull to disable the alarm?

Ali SC3

iTrader: (10)

not really sure but there is a connector you can pull to disable the horn, its just a speaker sitting in the engine bay by the battery.

SEIDO

iTrader: (1)

Glad I found this; has anyone resolved the issue, since the OP?

This has happened to me a few times before; however as of yesterday it's become more frequent.
It happened twice last night, and twice today (and will probably happen again later on, most likely).

What's the deal with this?
I've resorted to leaving the doors unlocked; which even though I live in a decent neighborhood, and the cars parked out back - away from the street, I don't like doing it.

Anyway, it's random.
I don't even have key fob; so it's not like I'm accidentally pressing the panic button in my pocket, or anything; the car just "goes off" ... ???

myLEXsc400

yes, so the issue is still happening with my sc400 randomly. I have come to the conclusion that it is in fact the wiring in the trunk on the passenger side. I took out the amp (so i no longer have any sound system working), and made sure none of the wires are touching anything. As long as that area is free of clutter, then the alarm doesn't go off. I have not gotten around to actually finding out which wire it is, and why its going this, because i've been working 60 hrs a week lately, and this is just my "beater" car.

t2d2

iTrader: (8)

Probably not your issue, but I had one such issue where it turned out I hadn't fully latched the hood. (Mine has to be dropped firmly from a foot or so. Pushing it down once it partially latches is never sufficient, even though it looks closed at that point.) I drove around with it that way not realizing it, then shortly after I got home that night it popped up on its own and set off the alarm.

I've had similar things happen with the trunk lid, where I'll have the car locked and the trunk popped but not fully open. Someone leans on the spoiler and sets off the alarm. I still haven't figured that one out, as closing the trunk wouldn't set off the alarm. Maybe leaning on it pushes it down enough to engage the alarm but not latch shut, so the bounce back sets it off?

At any rate, there's a couple things to investigate with things that appear closed but actually aren't, or vice versa.

myLEXsc400

hmmm, thats interesting. I doubt it though, since this car seriously does it completely randomly when nothing is around it. But I will investigate.

t2d2

iTrader: (8)

Actually, I was directing that to CityKnight. Your reply didn't show up until I had posted. Your issue definitely sounds like wiring.

SEIDO

iTrader: (1)

My pass. side trunk looks like this; so what wiring is it??? It's so annoying; I can't even lock my doors now, 'cus the alarm goes off about every 20min.

TheAzn

iTrader: (2)

So far I have fixed my random alarm trigger. My CF hood never latched all the way properly to lock down. I shaved part of it and has since got the CF hood to lock down. And my alarm hasn't gone off randomly since. Well, at least to my knowledge lol Maybe it has when I am not around.

I would say, best guess, wirings wouldn't be the issue. The components would likely be the issue. The trunk latch, hood latch, both door key holes, both door latches and both lock switches are tied to the alarm.

I would check/ replace the trunk and hood latches first since those are the ones that are always moving the most. Clean the wire connectors.

I am surprised that there hasn't been any concrete solutions to this. Maybe most of everyone who had this issue never gave a damn lol