993 Battery Drain

[John Henry]

My son has a 993 that he rarely uses. It's on a trickle charger but recently the battery packed up. We replaced the battery and while he was away on business the car was left off charge, soon dead again.

The electric windows work with the keys out and ignition off. Should this be the case? If not is it just a relay swap?

[bigfella70]

Windows will work with door open and no key in ignition. If door is closed they shouldn't work without ignition on 1 or 2.

Check for things like interior lights being left on either switched on inadvertently or faulty courtesy switches including engine compartment at luggage compartment, glovebox also.

Is the stereo switched off correctly.

Mine will last up to a fortnight before the battery drains, if I'm leaving it longer than a week I plug in my ctek trickle charger. Hard wired to battery rather than using croc clips.

Failing the above a decent auto sparky will get a multi meter hooked up and establish any current drain.

Hope you get it sorted ok.

[John Henry]

He noticed the courtesy lights were on after the car was parked in the garage, doors closed and engine off. Remedied by switching interior lights off.

I don't have access to the manuals on the car. Would the courtesy lights be on the same relay as the windows?
Windows are definitely working engine off, key out.

Would the switches for the interior lights be on the door shuts?

I'm unsure what to target first, don't have a multimeter and without knowing an auto electrician I didn't want to write a blank cheque..

[Wozy68]

John Henry said:

He noticed the courtesy lights were on after the car was parked in the garage, doors closed and engine off. Remedied by switching interior lights off.

I don't have access to the manuals on the car. Would the courtesy lights be on the same relay as the windows?
Windows are definitely working engine off, key out.

Would the switches for the interior lights be on the door shuts?

I'm unsure what to target first, don't have a multimeter and without knowing an auto electrician I didn't want to write a blank cheque..

Are you sure you still have a problem worth the hassle of trying to remedy?

Now its been realised that the interior light was left on and it seems drained the battery, does it really matter if the windows can be operated with the ignition off?

I'd be tempted to recharge or replace battery and see how it goes with battery drainage. My 993 will go easily 4 weeks and still have enough charge to start, no problem. I do have a nearly new 82H Bosch battery however.

[Pope]

Bear in mind the interior lights all share the same circuit; doors, boot and bonnet but also that the immobiliser unit supplies a delayed earth to the light circuit to allow time for the occupant to find key/switch on the ignition - iirc the delay is 2 minutes??

Connect an ammeter to the battery; lock the car up and see what the current draw is - spec. is < 50 milliamps / 0.050A

[John Henry]

The courtesy light issue came to light a few years ago. Internet research reveals a few threads detailing battery drain being a common fault on a 993. His car has the interior courtesy light issue. The electric windows also work without key in ignition.

Is this indicative of failed relay or switches in doors for courtesy lights? I was hoping someone may have had this issue. Current Bosch battery is weeks old.

I don't have a multi meter and I'm loathe to seek out an auto electrician if a relay is likely the culprit in this scenario. Thanks

[AW10]

With respect to the windows - they should work without the key when one or both doors are open but not when the doors are both closed. If they do work without the key and with the doors closed then the window relay is on - perhaps from a stuck door switch which is also turning on the courtesy lights. That current draw will rapidly kill a battery.

[996TT02]

I have no idea of the typical battery drain on a 993, so that's out of the way. But if there is anything significant, as there is on a 996, or even half that - and you don't mention how long your son was away on business for - if for anything over 2 weeks I would just disconnect the battery.

Obviously if there is a "problem" per se then that should also be seen to, but notwithstanding, I would still always disconnect.

Re the interior lights, if the lights remain on with the doors closed (and they are not put in the "always on" switch position) then as others have pointed out, a door switch must be faulty. Fiddling around with both of them will generally result in an identification.

[roygarth]

I fit one of these Discarnect battery master switches to all my occasionally used cars -

http://www.richbrook.co.uk/dis-car-nect-battery-ma...

[Merlin993]

There are plenty of topics regarding 993 battery drain, Porsche also released a bulletin regarding the matter. The simple solution is a multimeter placed in line between the negative side of the battery, so disconnect the neg earth of the battery [the alarm might go off!] connect the multimeter between the neg earth lead & the neg eart post on the battery. If you look up EricTheCarGuy on youtube he shows you exactly how to do it. Once you have connect the multimeter pull out each fuse in turn until you see a drop in the current draw, you should find your culprit. On top of the fuse box there should be a diagram stating what fuse does what. Mine was the radio/cd player which had been wired incorrectly. A must with any car that spends time sat in the garage is a battery conditioner, CTEK has been mentioned & is a wonderful piece of kit. You can leave it attached for months & it charges/conditions the battery. I have 3 of them! Good luck.

[roygrant4]

I have exactly the same problem, thought it was the battery but replaced it and went flat within day's.I currently have my car with the interior light in the permanently off position and the bulb removed from the bonnet light, the battery remains charge in this state. I have done all the drain tests and checked the switches, if you are in a quiet environment you can hear the relay working. My problem seemed to be intermittent so it took a while to do all the tests. My conclusion, after a lot of investigation, is the alarm, my next course of action was to call the manufactures for their advice but it could mean a new circuit board. Hope we can compare notes along the way.

[roygrant4]

I have exactly the same problem, thought it was the battery but replaced it and went flat within day's.I currently have my car with the interior light in the permanently off position and the bulb removed from the bonnet light, the battery remains charge in this state. I have done all the drain tests and checked the switches, if you are in a quiet environment you can hear the relay working. My problem seemed to be intermittent so it took a while to do all the tests. My conclusion, after a lot of investigation, is the alarm, my next course of action was to call the manufactures for their advice but it could mean a new circuit board. Hope we can compare notes along the way.

[mollytherocker]

Drive it.

[John Henry]

Thanks for the replies. As stated I don't own a multi meter.

So, definitively, the electric windows in a 993 DO operate with keys out of ignition but only if door open?

This indicates a relay fault if, as with my sons car, the windows remain operative with keys out of the ignition, doors open or closed

[shoestring7]

John Henry said:

Thanks for the replies. As stated I don't own a multi meter.

So, definitively, the electric windows in a 993 DO operate with keys out of ignition but only if door open?

This indicates a relay fault if, as with my sons car, the windows remain operative with keys out of the ignition, doors open or closed

http://www.ebay.co.uk/itm/Digital-LCD-Multimeter-Voltmeter-Ammeter-OHM-AC-DC-Circuit-Checker-Tester-Buzzer-/360538749861?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item53f1c8bba5

SS7