Weird Alarm Issue

[Dazsw]

Hi guys,

Hoping someone can offer some help.

We have an 07 Avensis 2.0 D4D Hatchback.

It has an intermittent fault with the alarm.

Basically when you try to unlock the car it won't unlock, you then have to use the key, soon as you open the door the alarm goes off, you can then start the car and drive it, after a minute or less the alarm switches off and all is well.

Most days the car is fine, we tried the spare key for a few weeks but the same fault occured.

It does appear to happen more on damp/wet days which leads me to believe water is getting into a sensor or some part of the alarm system, but can't seem to find it.

Had it checked at Toyota, no faults they say.

Even when the car decides that it won't unlock the lock function still works, just the unlock that doesn't.

Can anyone suggest where to try?

Thanks.

[revband]

On these the unlock function is on a rolling code, if the button is pressed too many times while away from the car it goes out of sync, not sure if it auto resets while the car is being used, but that may be what is happening.

[Dazsw]

Thanks for that mate.

Once the car is parked up for the day the keys get hung up and not touched again till trying to open it in the morning, so I would think that would rule that out?