Door Lock/Alarm issues
 

I have a 1999 Boxster, 5sp manual that has been having door lock and alarm issues. Basically, I get the double beep from the horn when I try to lock the car with the fob, and the dash switch does not work at all.

I removed the ECU from under the seat, removed the board, soaked it in 99% medical grade alcohol for several hours. I then drained it and dried it thoroughly. I also changed the ignition switch.

Everything works, including the window drop, windows, interior lights. Car starts and runs without a problem. The only thing that still doesn't work is the locking/alarm system. I get what sounds like a buzzing, grinding sound coming from the control module under the seat, and then the double beep from the horn. I still have the following codes:

25
60
34
46
47
61
58

I called the local dealer, and they told me that it is usually an all or nothing response from the ECU, and that it is very strange that everything works except for the door locks.

Before I spend the money for a new ECU and having it programmed, is there anything else that I can check or replace? Thanks for your help.

Rob

nomenclature
 

The immobilizer is under the seat, the ECU is accessed in the trunk.

Is the gas flap locking?

David

nomenclature
 

Yes, you are correct, I am referring to the immobilizer.

The gas cap flap does not lock.

Thanks,
Rob

update
 

I cleared the codes, and then tried locking the car with the key fob. I still get the grinding/buzzing sound from the immobilizer, the two horn beeps, and the doors do not lock. the only code that comes up is:

60

Is there anything else that I should try?

Thanks,
Rob

Did your immobilizer get wet? What did the board look like before you soaked it in alcohol? The 2 horn beeps indicates there is a fault in the system but if your immobilizer is making buzzing noises my guess is that you found your issue (which is unfortunate, as that is a pricy hit).

It would seem that the immobilizer did get wet. There was a bit of discoloration on the board, but no rust, which is why I was hopeful that I would be able to salvage it.

Do you have an idea of what the buzzing sound could be?

That sound could be a bad relay. It should either click on or click off. It's possible that it's not making good contact and arcing which may sound like a grinding/buzzing sound. Or it's not getting consistent voltage and clicking on and off very rapidly, making the buzzing sound. There's a guy on here who repairs immobilizers and yours sounds like it's a good candidate for repair. His username is Qmulus. I ended up repairing my own, but I talked with him a few times and he seems like a good dude. He'll save you a lot of money Vs. a new one or that other place in Florida.

And the dealer is full of crap. It's not an all or nothing deal. My immobilizer went bad and while window drop worked when I opened the door, they would not go down when I hit the button. The interior lights didn't work either. But the car started and ran fine.

Thanks, Piper, I will reach out to Qmulus.
I thought that what the dealer was telling me was a bit funny. He also told me that it would be $205/hour to diagnose, which is what he wanted to do.

Likely immobilizer
 

When I had the situation you are describing, (which I discovered trouble shooting my gas flap not locking).

It turned out to be the immobilizer board had gotten web and died.

My solution was to pull ECU and imobilizer, sent them off to these guys;

https://www.ecudoctors.com/

Wasn't cheap, however reasonable compared to other options.

David