Intemittent central locking failure

[Sailorman]

(Cross-posted from Rennlist)

First of all, greetings! I am once again a Porsche owner after 40 years (sold my 1965 356C when I graduated from university in 1975). I bought a 2001 Boxster S this winter, and just got it out of winter storage this month.

The problem I am posting is that the key remotes operate the central locking sometimes, but not others. I replaced the batteries in them yesterday and re synched the keys. That didn't work at first, but then it did, about 3-4 times in a row, with both keys. Then they quit working again today.

The passenger door lock seems ok, because it locks when the remotes work. The transmitters on the keys seem to be working, because the LEDs on the keys and on the dash flash. The in-car locking switch on the console works, and the trunk releases beside the driver's door work.

I did notice that, when the remotes are working, the horn honks when they are operated. I read somewhere that this is an indicator of something wrong.

So, my best guess so far is that there is some other intermittent fault in the central locking system. I have no idea where this system is and I haven't checked the wiring diagrams in the Bentley manual yet.

Any tips or tricks? Thanks!

[Scnell Gelb]

Do a quick check under the drivers seat for wetness. If the drains are plugged the electronics there get wet.

[Sailorman]

Originally Posted by Scnell Gelb

Do a quick check under the drivers seat for wetness. If the drains are plugged the electronics there get wet.

Thanks for the tip. There was wetness on the engine cover, too, so maybe there's a connection, thanks!

[Sailorman]

Good idea on the water/drainage, thanks. I just had the AOS done, and the mechanic told me that it was quite wet on top of the engine cover, so this may be related.

[Sailorman]

Update: Took the seat out and checked the immobilizer/alarm/central locking module under there today. Bone-dry, with a few crackling leaves to show that it hasn't been wet. And it worked, once, last night. So the unit may have an intermittent fault, but so far looks ok.
On the other hand, the locking switch inside has started lighting up, even though it's switched off and so is the rest of the car. It lit up by itself last evening in the driveway, but then went out by this morning.

Checked four drains in the back, and two in the front. They all run freely, and all the water comes back out (I measured). So good news that these seem ok, but still need to find out how the water gets in.

I'm suspicious of the weatherstripping at the front of the clamshell, even though it looks ok. But it was really wet under the back of the roof, and it could have spread from there.