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Poze123

2000 Porsche 996 - Battery Drains - The alarm Horn is a constant 3v an

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Hi all

This is my first post, having finally brought another 911. My previous Porsche was a 1985 Targa that I sold around 5 years ago when the Daughter was born (wish I kept that car!).

 

So, I own a 2000 996 Cabroilet and the battery goes flat within approx 5 days. I've read Loads of posts on various forums and have checked voltage and I have cleaned up the earth cables.  I loose about 0.1v per day, ie 12.5v Monday, 12.4v Tue, 12.3V Wed and by sat its like 11.85 and generally wont charge. I'm buying a big battery and CTEK next week, but I did notice a problem.  With the car running im showing 14.4v approx on my volt meter (on the battery) and 14.5 on the Positive terminal in the engine bay, so a little difference.

 

**So my question: **

I check the voltage on the battery each morning and I noticed that I could hear a Hum coming from the left of the battery, so the Drivers side on my RHD car. Its a very quiet fast clicking/humming noise. The noise is here when the cars unlocked and also when the Alarm is on (I setup a phone to record the noise with the bonnet closed and locked).

 

I removed the plastic cover to check and its the Alarms Horn thats making this little noise. I removed the plug and the noise of course stops, I checked the volage and its 3.3V and this is of course constant.         Is this normal? as I'm wondering if this could be one of the items draining my battery.

 

Tonight i will check how many millie amps this draws, but I just wanted to get this post up so maybe a Fellow 996 owner for a 1999-2000 car could open there bonnet and listen to their alarms horn (its noticeable when my road is quiet). :)

 

Many thanks,

Paul

 

Bournemouth, UK.

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It sounds like you have a parasitic draw on your battery and from your tests indicate  a possible short to ground on your alarm horns.

 

Using a volt-ohm meter (VOM). Connect it in series in AMP mode between the battery negative terminal (not positive side) and the ground cable. Also have all doors and engine cover closed and disconnect the trunk light. Measure your current draw. You should get a normal reading of about 50 or so milliamps (ma). Since your battery is going dead, your number will probably be much higher.

Watching the VOM you can then pull a fuse one at a time. I'd start with the fuse that runs the alarm horns.  When you pull the correct fuse the current draw will drop dramatically. Check against an electrical schematic and see what else electrical is on that same circuit and then thru the process of elimination find the culprit. 

 

You may have to re-wire a circuit (or two) to fix the problem. 
 

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Hey KB

 

Thanks very much for the reply - this is really appreciated and you wrote it in a very easy to understand way - thank you.

 

I'll do these tests mid next week  - thank you.

 

Just an an update in the meantime ---- I determined a couple of days ago that the Alarms Siren (black and red unit) was water damaged and completely destroyed. So Ive ordered a new Siren and Tilt Sensor. So this might have also had an effect as its obviously all linked to the alarm. IVe unplugged it and fitted a new battery and CTEK charger, the metal alarm Horn still hums, so once I fit the new Siren/Tilt, I can see if it still Hums and drains at 3v.

 

If it does, i'll do your test and reply with the info. The CTEK in the mean time is an awesome charger and naturally I put in a Bosch 80ah quality battery - so at least it will remain charged and in top condition whilst I sort the current drain fault.

 

Thank you,

Paul

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Hi KB

 

Good morning to you.

 

I have a further question for you , hope you see this and can let me know.

 

I'm going to finally look at the battery drain this weekend, so need to clarify something regarding the test process.

 

 

Process:

 

1) I open bonnet, connect my DVMeter inbetwen the negative battery post and the negative battery earth clamp.

2) Close the doors and put a screwdriver in the catch to trick the car into thinking the front bonnet is closed (so the light also goes out).

3) Lock the car. (?)

4) Wait 20-30mins and hopefully the DVMeter display will go down from around 900mah to around 50mah which i think is seen as normal. I'd expect mine to stay in the middle due to the constant 3.3V on the horn and a very quiet hum in the engine bay.

 

5) Question ---- I need to now Pull out 1 fuse at a time and see the current change on the DVM.   Am i meant to lock myself inside the car and press the lock Button twice on the key gfob, then wait 20mins,  so the interior alarm sensor dosent go off when i move? Or should i connect up the DVM and just sit inside the car and leave it unalarmed with the doors closed?

 

I just want to clarify the "pulling the fuses" out part, so I can look at this over the weekend.

 

 

 

Many thanks,

Paul

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I would just unplug the light in the front bonnet to take it offline and leave trunk open.  For the driver's door, leave it open and use a screwdriver to flip the latch to trick the car the door is closed.  You now have access to the fuse panel.  Remove the negative battery cable and then connect the VOM meter by clamping it in series between battery and negative cable.  Place the VOM meter in AMP mode and get reading.  Normal should be in neighborhood of 50 milliamps (ma) +/- 10 ma or so after some systems start to power down. Watching the VOM you can then pull a fuse one at a time. I'd start with the fuse that runs the alarm horns.

 

If you Google "parasitic battery drain" on Renntech or other sites you should get additional information. The Renntech Google syntax is below.

 

https://www.google.com/?gws_rd=ssl#q=parasitic+battery+drain+multimeter+site:www.renntech.org

 

I would recommend becoming a Renntech Contributor to have full access to other technical resources on Renntech like DIY, Technical Service Bulletins ( TSB's) etc.  Sign up HERE Good luck!

Edited by kbrandsma

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Hey

 

Thanks for the extra info, much appreciated and i will check that link in a moment.

 

Should I double-press the key fob? Ive never tried it, but i here it turns of the interior motion sensor?

 

I'll get this test done Saturday and reply back on the findings!

 

Thank you,

Paul

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Hello

 

So Ive made a video of my findings:

https://youtu.be/IFG2cgz8kas

 

Please take a look at this if you can. Ive never actually used the AMP setting on the DVM before, so I looked online and it mentions to connect the Red lead to the  Middle socket, for "ma". But when I did this and connected it in between the negative battery post and  the negative clamp, then set the dial to 200, it reads nothing and no power gets through the system, the entire car stays dead.

 

So I put the Red wire on the top socket and set the dial to 10Amp, this then gave me a display and looks accurate.

 

So on the video I have done what you mentioned above, once the alarm is set the display will go from around 80 to 38 after about 10 minutes, then fluctuate on 38-39,

 

Do you midn looking at the video and seeing if I have the meter setup right? Its showing 38 which i hope is 38ma, but maybe its 380ma?  I'm not sure.

 

I have some photos as well, but the video should show my setup.  I didnt have a chance to pull fuses as it was dark at this point, but im mainly keen at the moment to see if i have the DVMeter setup correctly and if im actually getting a draw of 38ma?

 

Many thanks,

Paul

 

 

 

 

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This might be useful: http://www.renntech.org/forums/topic/43659-battery-drain-an-interesting-one/?p=234343

 

If the alarm horn has a continuous hum and a constant low voltage feed, check that the alarm control unit (under the passenger seat on a RHD car) is bone dry.  If there is a leak, water accumulates in this area and damages the ACU, causing all sorts of problems.  If it is wet, get it out asap. remove the cover and dry it out.

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So on the video I have done what you mentioned above, once the alarm is set the display will go from around 80 to 38 after about 10 minutes, then fluctuate on 38-39,

 

Do you midn looking at the video and seeing if I have the meter setup right? Its showing 38 which i hope is 38ma, but maybe its 380ma?  I'm not sure. 

 

Your multimeter connection looks correct as it's on the 10A socket with the dial set to "10A". The number displayed should be in amps. So by 38, I assume you meant 0.38? That is 0.38A or 380mA, which is way too much and will drain the battery in a few days.

 

BTW, by connecting to the 200mA socket with the dial set to "mA", the large current (in amps) has blown the 250mA fuse inside the multimeter. You will need to replace that fuse before you can use that setting again to measure current that's < 200mA. That fuse would not affect your ability to use the 10A setting though.

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Hi all

Thank you for your responses, at least im getting closer to sorting the fault....

 

Richard - Thank you for that link, ive checked it and saved the image. I'll also look at the Alternator suggestion.

 

Ahsai  - Also Thank you. I must be drawing 380ma which makes sense. The car was 12.66 2 nights and now its 12.20 approx. I guess i'm loosing about 9Amps over 24 hours. I think the batterys 80Amps, its a really new Bosch one.

 

As I mentioned, the horn shows 3.3V constantly, so makes a small hum noise. There is also the very quiet hum from the engine bay.

 

 

I checked under the passenger seat a few weeks ago and the alarm unit looked really clean and dry. I did check the plugs and they all look great.

 

The Siren and Tilt Sensor were damaged by water. I did buy a really clean used pair, installed these, But I got a double beep and a double flash on the dash board alarm light, so something wasn't right there, so I unplugged these "new" parts (the internal battery did have a small amount of voltage).

 

 

So next up, i'll do the same job with the digital volt meter, then put the roof down, pretend to close the door and the bonnet, then pull each fuse. and check the meter as per KBs original idea :)

 

But if there are any other suggestions then let me know. I'm currently using the CTEK charger twice per week overnight to top up the battery  as I don't want it damaged as its brand new.

 

 

But want this sorted, need to keep the wife happy who already isn't keen on the Porsche.

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Also Ahsai, can I use my volt meter on the 10Amp setting still? I don't have any fuses to hand to repair the meter to use the other settings.

 

As per the video, the display shows -0.39 on this setting, I assume id be looking for -0.03 on that dial position?

 

I just didn't want to go through the tests on this setting, if it was a bit pointless and im better of going to a shop and buying fuses to repair the meter, then doing It?

 

 

Cheers,

Paul

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Also Ahsai, can I use my volt meter on the 10Amp setting still? I don't have any fuses to hand to repair the meter to use the other settings.

 

As per the video, the display shows -0.39 on this setting, I assume id be looking for -0.03 on that dial position?

 

I just didn't want to go through the tests on this setting, if it was a bit pointless and im better of going to a shop and buying fuses to repair the meter, then doing It?

 

 

Cheers,

Paul

The fuse only controls the 200mA and lower settings. You can still use your 10A jack with the dial set to the "10A" position because that 10A jacket is not fused.

 

I really can't see the meter's reading in your video but if your dial position is set to "10A" and the display shows "-0.39", that means -0.39A (or -390mA).

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Hi all

 

So I have an update and some new videos, and sadly I have Not identified the fault yet.**Please take a quick look at the 3 vids if you can**

 

So I connected up the Digital Volt Meter and checked the ma’s (millie amps) being drawn whilst the car was alarmed and after waiting around 30 mins. I’m drawing about 0.39, which is 390ma, which is a lot more than the expected 50ma. I charge my battery overnight twice per week to keep the battery in good condition.

 

So I pulled each fuse from the fuse box (I didn’t this twice to check)  and basically the meter would move slightly, but never go less than 0.39 (ie 0.37 for example), so the drainage issue isn’t on the Fusebox or a fused item! ****.

 

Next up I pulled the fuse from the aftermarket CD player to check the Eject doesn’t still work  - it didn’t. I also removed the CD player and unplugged it and I’m still showing 0.39.

 

I reconnected the new alarm Siren and the drainage went Up to 0.42, I guess the internal battery will be charging up as it only showed a small voltage when I tested it before installation (the original Siren was water damaged).

 

 

 

I then removed the passenger seat and removed the alarm control unit (not sure on its official name) and it looked visually externally and internally perfect. The two sockets/plugs were also perfect as was the Earth cable connections.

 

As an extra note, I also replaced the Ignition switch 2 weekends ago, just incase that was causing a fault.

 

 

 

New Ideas?

So I still get the hum and the 3.6v on the horn wire 24hours per day and the high pitched very quiet hum in the engine bay.

My dad has one of those temperature “guns” so I thought that maybe pointing this at various components in the engine bay when cold, might show me the faulty component? (or the one with power going to it, that’s making the noise). Ie the alternator might be a tiny bit warm (it doesn’t feel warm to touch and was new before I brought the car).

 

Anyone have any other ideas?  Relays etc?

Would an OBD2 reader or Durametrics show anything?

 

 

Thank you,

Paul

 

 

https://youtu.be/Fi1S1detN4s

 

 

https://youtu.be/InVdKf20iYM

 

 

https://youtu.be/A_ZnTA1ePno

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If you suspect it's the alternator draining current, you can do the following test with extra caution.

 

There's an engine jump start terminal right above the a/c compressor.  It's a black plastic box with the "+" sign on it (see the first and second photos here). Open that box and you will see a nut. Disconnect the battery first then remove the nut and disconnect the cable behind the nut. That cable connects to the battery's positive post permanently without any fuse so don't short it to the chassis or any engine metal parts!

 

The metal stud is one end of the cable that connects to the starter/alternator. Now insert your ammeter in series between that stud and the cable you disconnected. Once you make sure none of the metal connections can short to the chassis/engine, reconnect the battery. If you see the same 0.4A, that means your alternator/starter is draining the current and it's most likely the bad diode(s) inside the alternator.

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BTW, you can ignore and reconnect that alarm siren. It may be just a red herring. I think mine buzzes too. Also, there are devices that are NOT fused (by that footwell  fuse box) so if you still see the drain after pulling all the fuses, aftermarket stuff, and the alternator, it will be significantly harder to locate the drain.

Edited by Ahsai

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Thanks Ahsai

Good suggestion - I guess this would then purely show drain from the alternator to the battery and miss out on the other electronics further down the sequence.  So I really do appreciate the input. I'll do this alternator test  hopefully Thursday and i'll do it very carefully

 

 

I'm also trying to get hold of a wiring type flow diagram, so I can research things on there.

 

I did manage to find an Owners manual for a later 2001 car, so thats in the post and it may tell me something.

 

Other things:

1) do you think that plugging it into Durametrics would show anything?

2) Can i potentially pull relays one by one, near the fusebox? I dont know if they literally pull out (not tried yet).

 

Many thanks,

Paul

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Sounds like you may be on to something and that the alternator maybe the culprit.  This is pretty common and is usually caused by a faulty diode on the alternator.  Some replace their entire alternator which is quite expensive or you can simple buy the appropriate Bosch replacement diode and replace that for under $50.

 

As Ahsai mentioned don't short the positive side to ground.  :cursing:

 

Here's a video showing a similar problem. 

https://youtu.be/2x0o4-bNCvY

 

Good luck and keep us posted.

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There is a faster way to do it but you need to extra careful. You can hook up the multimeter like you did with your current setup (trip the door latches, hood latches, etc.) Then you can remove the nut on the jump terminal and disconnect the cable there. If the drain disappears, you find your problem. However, be very careful not to short your socket/extension/ratchet/wrench to the chassis/engine metal.

 

1) Durametric will be useful. It can tell you if there are any error codes in the alarm system. Bad sensors may prevent the alarm from going to sleep. Do you hear a beep or double beep when you arm your car?

 

2) They pull out with some force but I don't think it will help much as any power that goes them most likely is also fused.

 

BTW, before you did any measurements, did you wait for 1hr or so for the electronic modules to go to sleep first? There will be some normal current drain in the first 1/2 hr or so. Best is to measure at least 1/2 hr after you arm the car.

 

 

Thanks Ahsai

Good suggestion - I guess this would then purely show drain from the alternator to the battery and miss out on the other electronics further down the sequence.  So I really do appreciate the input. I'll do this alternator test  hopefully Thursday and i'll do it very carefully

 

 

I'm also trying to get hold of a wiring type flow diagram, so I can research things on there.

 

I did manage to find an Owners manual for a later 2001 car, so thats in the post and it may tell me something.

 

Other things:

1) do you think that plugging it into Durametrics would show anything?

2) Can i potentially pull relays one by one, near the fusebox? I dont know if they literally pull out (not tried yet).

 

Many thanks,

Paul

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Hi all

Thank you to everyone who has posted up and helped me on this issue.

 

I Think we have identified the fault --- or so I really hope!

 

I spent the evening outside with the torch on the 996, I took of the battery negative, removed the gold nut on the + jump start box in the engine bay. I then hooked up my Digital Volt Meter in the same way, so between the negative battery earth cable and the negative battery post.

 

I also unplugged the alarm Horn cable, as I didn't want to possibly have it go off with my neighbours close.

 

I then pushed down the latches for the engine lid and bonnet, then alarmed the car.

 

The amps dropped down from 2amps to approx 0.50  after 20-30 mins, so 500ma. I made 3 videos on this (see below if you have 5 mins in total).

 

THEN I removed the cable from the + jump point in the engine bay, I put something round it so it wouldn't touch anything but its short and doesn't move much. I rechecked the volt meter and I'm showing 0.05 (after 20-30 mins)!  so 50ma which is what I'm after!

 

 

So it looks like the alternator is faulty? or the Regulator on the alternator. I'm just double checking the wiring diagram later to check this, but from the posts above, it suggests the Alternator is at fault.

 

When I removed this fat cable, the hum noise also stops completely, so I'm guessing the alternator was making this noise (I've still to check the wiring diagram)....!?

 

 

I'll do some more research now and reply back -- but Hopefully its the Regulator as opposed to an entire Alternator. The Alternator was new, the previous owner had it fitted before I brought it, so I may be able to save a few quid and sort it under warranty, if not, I'll order a Regulator and fit this on Saturday!!

 

Thanks all, I'll check the situation now...! But I will be very happy if it is indeed the Regulator!

 

 

 

 

Edited by Loren
made videos viewable here
  • Upvote 1

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Removing the Alternator is straight forward  There's a great write up HERE

 

It also includes discussion on replacing the voltage regulator.

 

I would still recommend becoming a Renntech Contributor to have full access to other technical resources on Renntech like DIY, Technical Service Bulletins (TSB's) etc.  Sign up HERE

 

Good luck!

Edited by kbrandsma

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+1 on becoming a Renntech contributor!

 

Regarding your drain sorry to say but most likely it's the diodes and not the regulator. If the previous owner fitted a remanufactured alternator (most likely so as a new one is like US$600~1,000), it's not that uncommon for the reman ones to fail out of the box.

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I had my alternator rebuilt at a local electric motor repair shop 2 years ago. The tech replaced the internal parts then ran it on his test stand for the afternoon to charge batteries he had in his shop. Total cost $139.00. It might be to your benefit to look around.

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Love your videos! Shot in the dark...suspenseful and adventurous :)

I could hear your alternator humming. It's definitly draining power. 50~60mA drain is excellent.

What is thr green connector around the jump start box?

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