Alarm Problems (1 Viewer)

[larryt]

I've searched 11 pages of threads mentioning "alarm" with not much matching this problem. Here it is, in a 2000 LC:

My alarm (horn honking for 30-60 seconds) goes off intermittently. It used to be once a month or two, now it seems to be every day or few days. I am away from the vehicle often, so it could actually be every day. Usually it goes off in the late afternoon, at least that I notice. I don't think it has happened at night. It is usually parked outside. I do think the frequency has increased with the warmer temperatures in southern California.

Maybe this is related? I suspect that I might have a bad passenger door actuator. It acted up last summer in the heat. I tried to dig into it with a replacement from jonharis, but failed to remove the assembly. I will be trying again this weekend.

From other posts, I have tried cleaning the rear hatch light switch in the upper tailgate and resetting the alarm via the battery connect sequence, with no improvement.

Questions:

1. In light of all of the above, has anyone had this issue and fixed it?

2. Has anyone experienced the alarm going off when the door actuators go bad?

3. Is there any diagnostic tool that can tell me which door is the trigger?

4. Is there any way to lock the vehicle without setting the anti-theft system? Or to bypass it?

Thanks in advance for the info.

 

[Echelon]

My alarm use to go off a lot. I finally found a sensitivity adjuster under the cover for the gear shifter. Turned it down to 3 it was on 7, no problems now. It is a black box. Once you pop the facia off you should see it at the front. Mine is a European HDJ, so it could be different but worth a try. Also the alarm does not turn on if you lock it with the key instead of the clicker on mine.

 

[larryt]

Thanks Echelon. I will pull the facia off and see if we have that too. My manual indicates that the antitheft system arms with the fob or locking the doors, so I have to solve the underlying problem...or leave it unlocked.

 

[larryt]

Here's a wrap up to my own thread.

Actuator, actuator, actuator. I replaced three, but it was the rear hatch one that finally did the trick. No more alarm sounding from the heat.

Thanks to everyone who contributed to the actuator threads. Saved a ton of money doing it myself and solved a super frustrating situation.

 

[BullElk]

I am also having trouble with the alarm on my US '00 100. Is there a way to turn the alarm off completely?

 

[prerunner84]

I'm having a problem with my alarm my key fab will not work. if I open the door with the key the alarm will go off... could it be a actuator?

 

[Dwight S]

I'm having a problem with my alarm my key fab will not work. if I open the door with the key the alarm will go off... could it be a actuator?

Most likely...

 

[prerunner84]

Well this is over my head, for the life of me I can not figure out what the problem is. I replaced the lock actuator on the drivers door, reconnected the wires to the system so the door was recognized in the system and still the alarm goes off once the is unlocked and the door is open....I'm up for any advise ...ANYTHING!!!

 

[prerunner84]

Found the problem at last!! On back of each key lock there is a plastic sensor, (mine was the tailgate)..I'd say white in color..over time they get wore out and/or maybe just fall off.I thought I had a actuator problem but that was not the cause.. AGAIN if the key fab stops working and you open the truck with the key and the alarm go's off you might wanna look into this!
Thank you very much..Drive through

 

[larryt]

Great outcome. Glad you figured it out.

FYI: your PM inbox is full, so I couldn't reply to your last PM.

 

[CoolBreeze]

Found the problem at last!! On back of each key lock there is a plastic sensor, (mine was the tailgate)..I'd say white in color..over time they get wore out and/or maybe just fall off.I thought I had a actuator problem but that was not the cause.. AGAIN if the key fab stops working and you open the truck with the key and the alarm go's off you might wanna look into this!
Thank you very much..Drive through

Ok, just wondering how to fix the "plastic sensor" situation. I also have alarm going off when using the key, replaced driver's door actuator. Good for a few years, now it's back. Thinking of tackling the trunk next, but need a bit of clarity of what to do when I actually find the plastic sensor. (Sorry for bumping a 2.5 year old thread).

 

[prerunner84]

Ok, just wondering how to fix the "plastic sensor" situation. I also have alarm going off when using the key, replaced driver's door actuator. Good for a few years, now it's back. Thinking of tackling the trunk next, but need a bit of clarity of what to do when I actually find the plastic sensor. (Sorry for bumping a 2.5 year old thread).

I just stuck it back on the back of the key lock maybe zip tie it on prob take your battery terminals off and let your computer reset

 

[Stuckinthemud]

I just stuck it back on the back of the key lock maybe zip tie it on prob take your battery terminals off and let your computer reset

Resurrecting this thread again as this is exactly the problem I have. Nothing like standing beside your truck with the alarm going along at 6 am to focus the mind. Focused some of my neighbours’ minds too I bet. Maybe I am looking I the wrong pace but not finding the sensor referee to here. Can someone clarify its location please?

 

[Stuckinthemud]

I tried to remedy this issue by disconnecting the battery terminals in hopes that this would reset things. Also replaced battery in fob. neither worked and alarm still goes off whether manual or using the fob. So I dropped it at the dealer who checked and lubricated all latches, unplugged the horn and unplugged the sensor on the hood latch. They re-installed everything and declared victory. Suspected 1 or more of the latch sensors was not working. Unfortunately, as soon as I got home the trouble began again and the alarm once again goes off every time I turn the key or press the unlock button. Good news is the dealer did not charge me. Bad news is I am taking it back tomorrow morning for further diagnosis.

 

[reznunt]

I had the same issue and it drove me nuts... but I found the problem. It was a dirty driver door lock sensor. It's a small off white plastic piece with two wires coming out of it and it sits on the back of the lock cylinder. Opened it up and cleaned it out with electronic cleaner and added new grease. No more phantom horn honking and door locks actuating on their own.

 

[prerunner84]

Same here ,check all the sensors. Sounds like one of the sensors is telling the system that one of the doors are still in the lock position. Mine had completely fell off. it was the rear hatch sensor. I delt with it for a year or two

 

[Stuckinthemud]

Thanks for your thoughts on this. I am going to work on it today and will let you know how it turns out.

 

[Stuckinthemud]

So back to the dealership and left it with Lexus while I went to work. They determined that it was the sensor associated with the hood latch mechanism that was the culprit. So far, so good.

Lexus have been great about this. I have taken it back to them twice after my feeble efforts to tinker with this failed and they did not charge me for their time.

 

[prerunner84]

I guess them boys at Lexus need to start somewhere