ranithds

Hi, My 2003 Boxster has a 5 Amp draw on the battery every 45 mins which eventually totally drains the battery. The battery is new, and the alternator is working fine. If the car is run regularly there is no issue, but if I leave it standing for a week the battery is totally dead. Any ideas on what could be causing the issue? Because the parasitic drain is only every 45 mins it is a nightmare to find as I can't just pull fuses to see if the draw has stopped as I have to wait for 45 mins per fuse!!

Macster

5A is a pretty big draw. That level of draw is in the realm of a DME or security module or some navigation or other electronic gizmo kicking on.

But every 45 minutes? Are you taking the key out of the ignition and locking the car when you park it?

Do you have something plugged into the car's cigarette lighter? Is there some aftermarket stereo installed? Or possibly an aftermarket alarm/tracking device (Lo-Jack?) present?

If it is every 45 minutes it might be worthwhile arranging to be at the car when this happens to observe what happens.

ranithds

What is a DME?

This is when the key is out of the ignition and the car is parked, and locked.

Nothing is in the lighter, and although there is an aftermarket stereo fitted it has been installed for over a year and the issue only started in the last couple of months. There isn't an aftermarket alarm or tracker.

Schnell Gelb

From your Posts it seems unlikely you are going to whip out your Fluke and diagnose this using the Factory Service Manual.Which is what is required imho.
So it would be prudent to ask here for a referral to a competent ,honest Indie in your area ? It would be very easy to create a bigger problem .

mikefocke

DME - The computer that manages the engine electronics and pollution controls (DME = Digital Motor Electronics)

Other Porsche Acronyms here.

Always helpful to give your location and the model and year of the car you are talking about. Helps guide people trying to answer your questions.

The draw when off should measure in mA, not amps.

In some areas, cars are fitted with trackers while at the dealers. Owners sometimes don't even know they are there.

The interval seems like something is waking up and transmitting which takes a bit of power to do. Not just passively waiting for a key press. So it is connected to an always live circuit.

Has the ignition switch ever been changed? Ever given any indication of erratic behavior?

You can pull multiple fuses at a time to decrease the time to isolate. Once you determine the difference is in a group, then work within the group.

ranithds

Thanks Mike - I'm based in London, UK, and the car is a 2003 Boxster S.

The ignition switch has never been changed and has never given any indication of erratic behaviour.

The roof mechanism has recently been playing up - it won't close all the way unless I toggle it open and then closed via the switch and then it will close until I can operate the lever. Also the glove box wasn't connecting properly and so the alarm wasn't setting (one beep alert indicating a door not closed).

Could it be related to either of those issues?

Macster

With my 2002 Boxster every once in a while -- not very often though -- when I locked it the horn would sound which I took to mean something was ajar. The only thing that I suspected because it was the one thing most often used besides the driver door was the center console so I'd open then close the lid and almost always the car would lock with no further drama.

This went on for a while -- a few years -- and because it happened so seldom I just thought it was a marginal switch in the center console lid.

Then the passenger window would fail to drop when the door was open. Not all the time but often enough.

Yet another odd behavior appeared: The car door locks would lock on their own. I'd get in the car say at night after work and of course when walking up to the car I'd unlock it and get in. After getting settled in I'd start the engine and after a moment or two then I'd be busy backing the car out of its parking space and navigating the parking lot and notice the door lock LED glowing. I'd press to unlock and I'd hear the locks unlock and the LED would go out. But sometimes after a few moments the locks would activate again.

The final straw was when the passenger window would drop when the door was opened but then once open the window would go up again on its own.

Took the car in and the tech id'd the door lock controller the culprit and replaced this and symptoms gone.

I mention the above to highlight how a rather persistent but seemingly innocuous suspected marginal center console switch eventually turned into a bad door lock controller.

The same could be occuring with your car only it is the glove box switch you suspect.

In my car's case even while all the above odd activity was occurring the battery never ran down and I never had any indication of any out of the blue electrical load appearing.

But the car's security system and all the associated sensors and mini-controllers and such are pretty complicated and something could possibly fail in such a way to trigger a spurious security system issue that while it doesn't sound the alarm does wake up the security module which should be in pretty low power mode shortly after the car is locked.

A tech with the proper Porsche diagnostics computer can check out the car's security system and check for any errors which if he finds any can provide a clue as to what's going on.

In the meantime be sure the door bottoms are dry. The door membrane can fail -- due to age -- and let water from the wet side into the dry side and this can account for all sorts of odd electrical system behavior. In severe weather the water can leak from the door into the cabin and the car's security module is located on the floor under the passenger seat (USA cars).

While on the subject be sure the front and rear body water drains are free of any trash build up that can block water which can overflow into the cabin and if this happens you can kiss the security module goodbye.

ranithds

Thanks Macster - I'll double check that everything is dry and look to see if I can get a tech to check out the security system.

Is there a fuse I can pull to isolate the security system from the battery and see if that stops the drain?

Macster

From memory there are several fuses that I believe play a role in the security system. My reference (Bentley Boxster manual) is at home so I can't take a peek to refresh my memory.

There should be a chart on the inside of the fuse box lid that lists the fuse assignments. Be aware that often a fuse is associated with more than one circuit so if you pull a fuse thinking it will disable the security module it will but it might also disable something else. The something else might not be anything important -- relatively speaking or it might really complicate things. The Bentley manual lists all the circuits associated with each fuse.

(When the spoiler on my 996 Turbo was acting up due to hydraulic system leakage I disabled the spoiler by pulling the "spoiler" fuse. However unbeknownst to me at the time it also disabled the engine lid latch and while I could check the oil level as always from inside the car when I went to open the lid to add oil the lid wouldn't open. At the dealer a tech id'd the "problem" and after he installed the fuse was able to open engine compartment lid with no problems. Because the failure to unlatch of the engine compartment lid with just the "spoiler" fuse removed actually had a tech suspecting something wrong at first there was no charge for this diagnosis.)

sniperonhigh

Does your steering lock work? When you pull out the key after turning off you should hear a "clunk". Also does your engine compartment cooling fan work as it should. Just curious if the fan circuit and timer was fried and the fan was locked up it could cause such a draw.

ranithds

Hi Macster - thanks for the advice. I'll take a look and check the fuses in sections that make sense.

At Sniper - I'll check the steering lock. I don't recall it not working but also can't recall having made sure it worked recently. The cooling fan all seems to be working ok - but again I'll check it is cooling properly.

sniperonhigh

The ignition switch isn't really "off" until the steering lock engages. On my 01, the radio still plays after turning off, but when I pull the key it shuts off. Also it is cheap and fairly easy, so if you haven't ever replaced it I would look in that direction.