Battery current draw depends on alarm on or off

[Jorge Llacer]

I have this 1999 Carrera 2 in excellent condition, except that if I am not careful, the battery will get discharged in perhaps one week. My very experienced independent Porsche mechanic has found that battery current when the engine is off, key out and door closed becomes approximately 140 mA, measured with an ammeter in series from the negative of the battery to chassis. However, when the car is alarmed, by locking it or using the key fob, the current becomes approximately 30 mA after about 14 minutes and, in that condition, the battery will last probably weeks without causing any problem. I am pretty good with electricity and I have reviewed his measurements and, sure enough, he is right. He already tested removing fuses one at a time, without success. I have read postings and responses in this forum, but nothing appears like a possible cause. My mechanic does not feel comfortable in recommending the purchase of a new alarm control unit, he is not sure that spending the money would lead to a solution. Does any one have any clear ideas about this rather well defined measurement and what it could mean? Thank you very much.

Jorge, San Jose, CA

[Loren]

:welcome:

Normal is 30-40ma at rest - locked or not.

Do you get a beep (or two) when you lock the car?

[Jorge Llacer]

Hello Loren:

Yes the car bips when I lock it.

Jorge

[Loren]

Then you have an open zone - in normal operation there is no beep.

Best to find Durametric, or PST2 tester, or PIWIS tester to find out exactly which zone is open.

The switch or sensor that does not change state maybe your problem. A common one is the front hood microswitch - if this fails the truck light is always on.

[jimmy3530]

Loren:

Do you have a part number for this microswitch?

[Loren]

Yes, (it is below) but this is just a guess without the fault code. One member put a video recorder in the front trunk and recorded the light still on with it closed to confirm his issue.

I hate to see people buy parts they may not need.

996-613-206-00 Microswitch -- US MSRP $79.22

[Jorge Llacer]

Hello Loren:

I will follow up on the idea of the open zone. Thanks for the names of the testers needed, I'll see what mechanic I can find that can use one of them.

If the problem gets solved, I will post it here.

[biopsea]

loren amazes me with his knowledge. !!!!! for what its worth, i have never gotten a beep when locking, but since i drive the car so infrequently, i purchased a Porsche battery tender. you can buy it for less without the P car logo but......

[Karl996]

Slightly off topic but is the engine compartment light linked to the luggage compartment light.

I've noticed when the luggage compartment is open the engine compartment light is on as well.

Just thinking that that might be easier than a camera in the front.