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So my daughter is home for Thanksgiving break with a dreaded parasitic battery drain. Did a quick check with the ammeter and found when I pull fuse 43 the drain would reduce from 0.38 to 0.05. Looks like that could be the circuit. But now I have no idea what that circuit controls … all I can see is Engine Control Elements. Any thoughts or ideas? One other piece of the puzzle (maybe) … she did “run over” some road debris --- maybe she hit a relay or wire or something in the process? Any help is greatly appreciated.
 

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Fuse 43 is for the secondary air solenoid valve, EVAP purge valve and both O2 sensors. It is switched by the fuel pump relay, so when that relay is off power will be shut off. Chances are this is not the problem. You may need to close the doors and wait a couple minutes for the ECU to shut off the power.

Around .05 amps is a normal drain. Did you see my DIY on parasitic drain?

http://newbeetle.org/forums/questio...0356-how-test-parasitic-drain-new-beetle.html
 

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The Monsoon amp is a common cause for battery drain in these cars. If yours has this, I'd disconnect it (or pull the right fuse) and see if the drain goes away.

Our NBC had a drain that would kill it if it sat for more than a day. On ours, there is no Monsoon amp, but the radio in the dash was causing a drain. I pulled the radio out of the car and the drain went away (it started right up after sitting for the weekend). I'm guessing it had to do with the malfunctioning CD player in the unit. On many cars, they will let you eject the CD after you shut off the car.

I replaced the faulty VW unit with an aftermarket Pioneer head unit from Crutchfield since they throw in all the adapters and the dash kit if you spend enough on the head unit. If you go this route, be careful of the "K-line", or else you won't be able to scan the computer for problems: http://www.ross-tech.com/vag-com/aftermarket-radio.html
 

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This is my exact issue. I have pulled every other fuse with no drain indications. I get a normal draw reading at .04 without Fuse 43. After I close the door, it stays at .09 for about 20 secs, then drops to .04. When the fuse is in, I get .54 after closing the door, then it drops at .49 after 20 secs. I waited 15 mins to see if the fuel pump relay would shut off, but nothing ever changed during that time. It stayed a continuous .49 draw. I then pulled the fuse again, and 20 secs later, it's back down to .04.

So do I start swapping out the secondary air solenoid valve, EVAP purge valve and both O2 sensors one at a time?. Do I replace the fuel pump relay? Any ideas?
 

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About the only explanation is that the fuel pump relay has welded its contacts together. Remove the relay and see if that also gets rid of the parasitic drain. If so, check the resistance between pins 17/30 and 23/87 on the relay (those are the labels on the schematic, not sure how it will correspond to the part). It should not be 0.
 

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99 NB Parasitic Drain

Hey there Red99. I'm the guy with the 99NB with the parasitic drain that you spoke to about 6 months ago. I still have the problem but finding it has been a different story. However, after reading several different threads regarding this problem I realized I may have set my multimeter to the wrong setting. I'm getting ready to run through the process again and hoping I find something. By the way, the last time I did the test, instead of opening and closing the door several times I simply manually closed the door latch, which I believe has the same effect--simulating a door-closed condition or is there something I'm missing? Also, I've read some threads that discussed removing the fuses up under the dash and checking for a draw. I hadn't done that before, due to access issues. Would you suggest removing the under-dash fuses as well? Thanks again. KC
 

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If you are using the 1 ohm resistor like I suggest in my DIY, then you should be using the millivolt scale on the multimeter. The parasitic drain in milliamps is equal to the millivolt reading on the meter.

Manually closing the latch with the door open is completely equivalent to closing the door. That's a great idea to make the testing quicker. You can just pull and replace fuses without needing to go through the close door and wait cycles.

Nearly all the fuses are behind the door. The ones under the dash are for higher amp things like the power window motors aren't likely to be the problem. I'd definitely check all the others first.

The problem could be the alternator as well. If removing the leftmost (large, black) cable on the battery fuse panel eliminates the drain then the alternator or voltage regulator is bad.
 

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Red, I am performing the parasitic draw test with two different meters. My old meter is set to "dc volts" and the dial is set on "20" and with the door open and no fuses pulled it is reading "0.04" volts. When I pulled all the fuses, this reading stayed at "0.04" until I pulled fuse #14 "Interior Lighting". When I pulled fuse 14 the reading went from 0.04 to 0.02. On the new meter, I have the red lead in the "10A" slot and the black lead in "com" and the switch is set at "10" and with the door open the meter is reading "0.3" The reading stayed at 0.3 until I pulled fuse 14, then the meter went to 0.1. Would these readings indicate a significant draw? Can I assume my parasitic drain is being caused by something in my interior lights? Fuse 14 is also for the central locking system which conjured up bad memories. When I first acquired the new Beetle and discovered the parasitic drain problem one of the first things I replaced was the driver's side door locking mechanism because the locking mechanism seemed to be the most common cause of parasitic drain (plus it was 15-years old and seemed to work intermittently, plus it sometimes set off the car alarm for no apparent reason). Anyway, back to fuse 14--could this really be my problem? It seems so simple. Have you ran into anyone else who isolated their PD problem to the interior lighting system? If so, do you recall what they did to fix it? Thanks for any and all feedback. KC
 

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With one meter you are using the volt scale and the other is amps. Are you using the 1 ohm resistor like I described? If you want to use the amp scale you would need to use the meter directly without the resistor. Also, did you defeat the door switch by manually closing the latch?

There is a light in the glove box. It may be worth removing it and seeing if your readings change.
 

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Hey Red, thanks for the quick response. Yes, I've used the resistor every time. Didn't realize I wouldn't need the resistor on the amp scale. Yes, I manually latched the door as per our previous discussion. In your opinion, do you think the drop was significant? I've watched dozens of youtube videos regarding parasitic drain/voltage drop and it's still a little confusing. As for the glovebox light, I'll try that and see what happens. About a month ago I was checking every connection I could find with my meter and realized the glovebox light was burnt out. I replaced it and it's working fine now. I also replaced the horn relay when the horn didn't work and the fuse was good but no power at the horn. At that time I discovered a few strange things worth mentioning. 1. In the horn/foglight/running light harness beneath the left front fender there is an extra connector that deadheads just below the fog light. It isn't connected to anything, yet with the lights on it was reading 8.5 volts. As my kids would say "smh" shaking my head. 2. As I was troubleshooting the horn problem I removed the relay panel for easier access and discovered two wires with in-line fuses that were attached to two of the relay panel posts. The wires were soldered together and routed up under the inside door molding and heading in the direction of the sunroof. My sunroof works fine, so just for fun, I pulled one of the fuses and tried the sunroof and it didn't work, leading me to believe that a PO had a sunroof problem and decided to rewire it himself. Don't think it has much to do with parasitic drain, just thought it was interesting. If I hadn't found it and had a sunroof problem I would be doing a lot of extra troubleshooting. Anyway, I apologize for being so long-winded. I just figured by now you'd seen about everything. I'd really like to know what that extra connector in that horn/lighting harness is used for. I'll holler back after I recheck without the resistor. Thanks again. KC
 

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The two readings you have made are inconsistent if the resistor is actually 1 ohm. The .04 volt reading indicates .04 amps of draw whereas you measured .3 amps with the ammeter. The resistor will have little effect on the ammeter reading, so that should still be accurate. The readings would be consistent if the resistor was more like 0.1 ohms. Anyway, I'll put the most faith in the ammeter reading. 0.3 amps is consistent with a single interior light bulb staying on. The things powered by fuse 14 are:

Trunk light
Right and left reading lights, about the doors
Right and left makeup lights behind visors
The front interior light on the rearview mirror

The connector near the foglight sounds like the exterior temperature sensor connection. Does the exterior thermometer work?

The sunroof may be somewhat of an afterthought on VW's part and I wouldn't be surprised if the electrical connection for it is a little more kluged than the rest of the wiring.

So, is your horn working now? Was the problem the relay?
 

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Red, yes the horn works now, but after I went back over all the steps involved, and considering the delay in getting the part, I'm not sure but I may have made a technical error by installing the relay in the open slot instead of the horn relay slot. Anyway, the horn works now. As for the interior lights, I just ops checked the light switches in the car and most of them seem to be working properly, however, the switch on the bottom of the rear view mirror is a 3-position switch, in the first position the light is off, in the second position the light came on, and in the third position it didn't change, the light just stayed on. Is that by design? The strangest thing I found was in the driver's side mirror light. When I flipped the mirror lid open, the light came on. I then tried it a few more times and about the third time I heard a "click" but no light. I then flipped the lid open and closed several more times with no light. Just when I was beginning to think I had a blown bulb, the light came back on. So the light, (when it decides to come on)comes on when the mirror lid "clicks". So, the switching mechanism in the mirror hinge sometimes works and sometimes doesn't. What if that switch still receives power after I turn off the car? And, since my drain problem is intermittent, and this switch seems to work when it wants to, could this be my elusive parasitic drain problem? I appreciate your help with this. KC
 

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The power for fuse 14 is not switched, so anything powered by it can come on even with the ignition off. I would try removing the suspect makeup light and see if that fixes the problem.

The center position of the rear view mirror and reading light switches is the "door" position. It comes on when a door is opened and is shut off by a timer after it is closed. The default for the timer is about 30 seconds, but it is something that can be programmed with VAG-COM.
 

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OK, that makes sense. I sure hope it's something that simple. If it does fix the problem it will take a few weeks before I'll feel confident, since the battery drain has been intermittent. In any case, I appreciate you helping me narrow it down. I'll let you know what happens. KC
 

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Red, just to double check (triple, quadruple check) I did the parasitic drain check again just for the suspect fuse 14. With the meter hooked up to the resistor and the dial on "20" I re-verified that meter read ".04" with fuse 14 installed, and ".02" with fuse 14 pulled. I removed the makeup light bulb and the reading stayed the same (as it should, correct?) Then I reinstalled fuse 14 and my reading went back to ".04". As near as I can tell, I am at the point where I'm going to check my battery daily to ensure I'm not having a parasitic drain problem. So with that said, I'll keep checking and I'll let you know what happens. Much thanks again for your patience and help. KC
 

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There is also a connection to the central control module for the comfort system through fuse 14, so that is probably where it gets its power from for the electronics. If you are using a 1 ohm resistor then .04 or .05 is a normal reading for everything off. The drop of .02 could just be the keep-alive for the central control module. If your meter has a millivolt (mV) scale, that is the one you should be using.
 

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I'll double check my meter for Mv, not real sure about that. OK, I definitely don't claim to be an electrician, so I'm looking at my meter now. It's a Commercial Electric model MAS830B. On the DC voltage portion of the dial the selections are as follows: 600, 200, 20, 2, and 200m. For the parasitic drain check should I have it set on 200m? I know this is a lot of information, and a lot of questions, I just want to be sure. Didn't know that fuse 14 powered the other items you mentioned, which is good to know. As for the battery, I've checked it 2 days in a row (with a meter, not trying to start it) and it has stayed at 11.8. I'm crossing my fingers because the voltage has never stayed that steady for more than a day or two; it always starts creeping down a little bit each day until the car won't start. I'll keep you posted. Thanks again.
 

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The 200m scale is millivolts, so that is the one you should be using for the tests.

If your battery voltage is 11.8 even right after shutting off the engine, then either it is not getting charged properly or it is old. First, make sure the water level is OK if it is not maintenance-free. Add distilled water if needed.

To check the charging system, right after a cold start the battery voltage should be 14.0-14.5 at idle. After driving 10 minutes or more it should be above 13.8 at idle.

To check the battery condition, after driving 10 minutes or more, shut off the engine, leave the parking lights on for 1 minute and shut off the parking lights. The battery voltage should still be above 12.4. Once it starts to get below 12.4 your battery needs to be replaced.

These are guidelines for checking the battery. Many of the parts store chains have battery testers that they will use on your car in the parking lot. If you do that, make sure that it is charging properly first because they may not differentiate between a bad battery and a bad charging system.
 

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Wow, I'm so accustomed to seeing the non-running voltage below 12 volts that I guess I thought that was normal. The battery was new in July 2014, a few months after we got the car. At that time we hadn't heard of parasitic drain and the local parts store said our battery was bad, so we replaced it. I just double checked and it is a maintenance-free battery. Over the past 14 months, because of our PD problem, I bet I've charged (or jumped)that battery 20-25 times (and that's probably a low estimate). I don't remember who I asked, but it was someone on one of the forums; I asked them if the battery going nearly dead multiple times could gradually affect the battery's ability to hold a charge, and they replied that it could. At the time I was skeptical (plus, I was sure I would eventually discover the PD source). Anyway, I'll do what you suggested. On a related note I also read that a bad diode in the alternator could cause a PD, so I removed the alternator and took it to Advance, Autozone, and O'Reilly's and all three said the alternator was good. If I get a new battery I think I'll feel like "here we go again". Thanks again, and I'll holler back later.
 

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My estimate is that if a starting battery has been drained flat 5 or 6 times it will be toast after that. It is very hard on a battery intended for starting to be drained all the way. That is what "deep-cycle" batteries are for.

Make sure your charging system is up to par, but it sounds like you may need a new battery.
 
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