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An Annoying Alarm Problem

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Hi all,

On my 1990 gen 1, about 50% of the time, whenever I unlock the car (I only ever use the key) the [original] alarm goes off. So far I've always been able to cancel it by relocking and unlocking the car. Sometimes it just gives one toot. But either way it's a little embarrasing, and I've no doubt that one of these days it's going to leave me stranded.

I have the 1991 Lexus repair manual (2 volumes) which does have some useful information but does not show a truth table with the status of all the door switches etc. in any given mode. It also shows a separate alarm horn in the engine bay just in front of the bulkhead, which I thought of disconnecting until I can get this sorted properly (and to avoid upsetting the neighbours when I'm working on it). However, my car does not seem to have this - presumably using one of two main horns for the alarm. Anyone else on here had this specific problem? Any advice gratefully received.


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The Battery (genuine Toyota) is only a few months old. The problem I'm sure is more to do with the switch block in the door(s) which tell the alarm ECU whether the door has been unlocked with the key or from the inside when it's still keylocked. Either dodgy switch contacts or something with the mechanical linkage that actually operates the switches. I'm coming round to the fact that there is no easy fix and I'll just have to take the door panels off and work round the car. (Great - I can hardly wait!) It would just be nice to disconnect the alarm hooter (assuming that on this model year it is separate) but I guess I could just pull the fuse...

Thanks for reply anyway...


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There is a small switch directly behind the door key,

this went faulty on mine, this stopped the doors from locking, and thereby setting the alarm.

It is fiddly to get at but you can do it with the trim off.

Whilst mine was off I removed the lock mechanism [ equally fiddly ] but

links and rods showing signs of rust and no lubrication were fixed at the same time.[recommended]

Pity you can't put it off until warmer weather


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