Parasitic Draw - must doing something wrong!

CoolAirVw said:

Door harness can fail and cause parasitic drain on 06. Seen it 3 times. Open up the "accordion" and see if wires are broken.

Dont know how to tell you to diagnose though.

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That was actually the first thing I did last night and the wires looked fine. Additionally, I'm getting no vcds faults from the door, everything electrical works everywhere as near as I can tell. Kinda stumped other than the radio, which I'm not even sure where to start on that. It seems that it's more than the radio, too, as the draw seems bigger than 100mA.

Thanks for the input.

FletchMan said:

I did note this on my own as pulling a fuse did nothing while reinserting it jumped up the draw. To combat this, I both tested all the fuses without pulling them (after plenty of time to let it go to sleep) and then pulled them one at a time without reinserting them - at least those drawing power using the first method.
A couple days ago I hooked up the trickle charger to the battery while still in the car. It pulls enough current that it's going to take a battery that was about 12.1V about 3 days to get back to 12.6V so the drain isn't much slower than a trickle charge.
I'm more perplexed after knowing all the power goes through the panel under the hood. I did leave the battery unhooked but jumpered to the cable overnight to give plenty of time to go to sleep. I'll put my multimeter in line and give it a go again tonight.

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Sorry if I'm reading this wrong, but you still pulled fuses? That was the whole point of the highlighted quote - don't even pull fuses. I have gone on wild goose chases on Beetles by pulling fuses.

Which fuses still have draw? And have you unplugged the radio to see if the rest of the draws go away?

If you were closer to Nashville I'd stop for a few and help out.

Jason

SilverGhost said:

Sorry if I'm reading this wrong, but you still pulled fuses? That was the whole point of the highlighted quote - don't even pull fuses. I have gone on wild goose chases on Beetles by pulling fuses.
Which fuses still have draw? And have you unplugged the radio to see if the rest of the draws go away?
If you were closer to Nashville I'd stop for a few and help out.
Jason

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I pulled fuses at one point but last night I left everything plugged in and used my meter on the fuses while they remained plugged in after giving it a few hours to completely shut down (with the hood and door switch tripped).

There are two fuses that still have draw - according the mV readings across the fuses and the matrix in the technical bulletin, the radio is pulling about 100mA and the sunroof control module pulls around 50mA. What's odd is I believe the overall draw is double those amounts.

Here's what I'm thinking of doing next. I'm going to measure draw by pulling the negative cable but jumpering it to the battery post to let it sit while the system goes to sleep. I'll then put my meter inline, remove the alligator clip so the current is only running through my meter. That should give me the total drain minus the sunroof and radio, correct? Anything wrong with this plan?

By the way, can someone explain what the bigger 50 amp fuses (big in literal size) under the hood do? Am I supposed to be measuring the draw on these, too? These are certainly contributing to my draw problem but I thought maybe these are some sort of central power source from the other fuses. When looking in the manual the big 40 amp fuses are turn signals/headlights but there's nothing mentioning what the 50 amp fuses are.

weak battery? Try disconnecting battery and letting it sit for two days and then reattach to see if it will start car.

CoolAirVw said:

weak battery? Try disconnecting battery and letting it sit for two days and then reattach to see if it will start car.

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The battery was tested out and recharged at interstate battery store. While disconnected, it holds steady at an appropriate voltage. The big draw in a resting state is evident using a multimeter...pulls hundreds of milliamps versus the 30 the book states it should be pulling.

I removed the radio and sunroof fuses and let it go to sleep again while putting my meter in line with the battery to better measure total draw. The readings won't settle and are all over the place. Ideas on what that means?

When the current readings won't settle and keep going up and down - that sounds like a control module waking up one of the CAN busses.

VCDS can show MVB in gateway of all the control modules and their status (sleep, away, no comm) and status of the busses themselves. Obviously there is going to be draw because gateway module is awake and VCDS is comm with it.

Word of caution - sometimes it will show which control module(s) is(are) awake, but NOT which control module or sensor is keeping them awake. IE: dead/no comm from control module causing others to stay awake.

Jason

PS - you in South Dakota?

SilverGhost said:

When the current readings won't settle and keep going up and down - that sounds like a control module waking up one of the CAN busses.

VCDS can show MVB in gateway of all the control modules and their status (sleep, away, no comm) and status of the busses themselves. Obviously there is going to be draw because gateway module is awake and VCDS is comm with it.

Word of caution - sometimes it will show which control module(s) is(are) awake, but NOT which control module or sensor is keeping them awake. IE: dead/no comm from control module causing others to stay awake.

Jason

PS - you in South Dakota?

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I let it sit overnight with the radio, sunroof, and an unidentified 50amp fuse pulled. It still pulls a little over 50 milliamps at rest. That is still beyond spec so I'm just stumped. That's assuming I can fix the radio and sunroof problem...and a problem I don't even know where to start. Didn't think there was a problem that would stump me like this but I'm about to give up.

Thanks for your insight...and yes, the Black Hills of South Dakota.

I need to get a better understanding of how I can use VCDS to really look at these modules.

It seems like it would be impossible to use VCDS (with the key on) to determine these other things, though...what am I missing?

The ECU software is very simple, not comprehensive and only looks for specific readings from specific sensors. It's not great for mechanical failures and the electrical system at it's core is mechanical.
There's a good guide over in the OBDII forum but it was written in the VE era. Haven't seen a good one for the PDs. Ross Tech sells a manual, but most of us learn a little at a time using this interweb thang.

Makes sense to me. In the meantime I can start trying to fix the problems I think I have - sunroof and radio wiring. This should be fun.

Thanks!

FletchMan said:

I need to get a better understanding of how I can use VCDS to really look at these modules.

It seems like it would be impossible to use VCDS (with the key on) to determine these other things, though...what am I missing?

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Gateway (19) - MVB 125 and up should be CAN status of control modules. Oh, and Gateway works with key off (once you have MVB up and displayed).

So get setup with all your MVB showing the control modules you want to watch and turn the ignition off. Watch to see which buss and control modules go to sleep and which stay awake.

Jason

SilverGhost said:

Gateway (19) - MVB 125 and up should be CAN status of control modules. Oh, and Gateway works with key off (once you have MVB up and displayed).

So get setup with all your MVB showing the control modules you want to watch and turn the ignition off. Watch to see which buss and control modules go to sleep and which stay awake.

Jason

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Good information! I'll give it a whirl. Thanks.

Could it be a bad diode in the alternator?

robm2 said:

Could it be a bad diode in the alternator?

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I just read something this morning that made me think about the alternator. It is still charging just fine. Could it be charging ok but still have a problem?

I have traced the problem circuits to the fuse and sunroof, though. I'm going to try to fix that first and see where I stand....or I'm just going to run it off a cliff.

Thanks for the thoughts to ponder.

The problem could indeed be related to a diode in the alternator that is allowing current to back feed through it. It will cause a meter to vary its readings wildly because the silicone gates break down unpredictably until they actually fail. Disconnecting the main power wire between the alternator and the battery should prove it one way or the other.

-Rich

Check current flow to the alternator as well when doing you parasitic draw tests.

Or just drive for a while to charge up, then disconnect the alternator cable from the front of the fuse box. If your draw is gone or the car starts fine in a couple days then that's it.

Generally should be the largest fuse and furthest from the driver side (closest to passenger side). NOTE: fat red cable is from battery, fat black cable next to it should be alternator cable)

Jason

SilverGhost said:

Check current flow to the alternator as well when doing you parasitic draw tests.

Or just drive for a while to charge up, then disconnect the alternator cable from the front of the fuse box. If your draw is gone or the car starts fine in a couple days then that's it.

Generally should be the largest fuse and furthest from the driver side (closest to passenger side). NOTE: fat red cable is from battery, fat black cable next to it should be alternator cable)

Jason

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I haven't had much time lately but I don't think it's the alternator. Three days ago I charged the battery, pulled the sunroof and radio fuses and parked it. It started, no problem, this morning.

So, now to track down the radio and sunroof problem.

Thanks for the thoughts on this.

FletchMan said:

I haven't had much time lately but I don't think it's the alternator. Three days ago I charged the battery, pulled the sunroof and radio fuses and parked it. It started, no problem, this morning.
So, now to track down the radio and sunroof problem.
Thanks for the thoughts on this.

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Hang in there Fletch! Sounds like you are getting close. One thing about these cars is that they can have some unique problems.

I have 03 beetle chased a parasitic draw for over a year. Turned out to be the alternator finally got to a point where it would only give about 13.2 volts when idling and sometime never higher then 10.9. replaced alternator back to constant 14.3

aja8888 said:

Hang in there Fletch! Sounds like you are getting close. One thing about these cars is that they can have some unique problems.

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Ugh. The radio is aftermarket and I have a harness that fixed the battery drain problem when replacing stock...so I'm thinking there might be a short somewhere. I guess I'll try to remove the radio, first, and see if that's the culprit. If not, it has to be the wire somewhere...right?

The sunroof...maybe it's the module that has a problem. Guess it could be the wire, too.

Maybe I'll install a toggle switch for these two items and run it to the dash.

phawkins224 said:

I have 03 beetle chased a parasitic draw for over a year. Turned out to be the alternator finally got to a point where it would only give about 13.2 volts when idling and sometime never higher then 10.9. replaced alternator back to constant 14.3

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That's a weak charging system. A parasitic draw is when it drains while inactive.

To test the alternator for a bad diode, measure the output for AC volts. If it is just one bad diode, the regulator can make up for it to a certain extent, so it will output what looks like the right DC voltage, but it will have lots of AC on it that the regulator and your DC meter can't see. Any more than about 50 mV AC is an indication of something wrong.

BobnOH said:

That's a weak charging system. A parasitic draw is when it drains while inactive.

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Yes, mine is definitely a draw beyond VW specs. People do sometimes confuse the two as the assumption is that the battery would be fully charged after a long drive time. When you come back and it's not, then you realize you have a problem and figure since it started fine last time something happened in the meantime. I meant I was't ruling out that alternator isn't also problematic as far as contributing to the draw...but I do know that's not the only problem for sure.

Maybe this isn't that odd of a happening but one thing I've had happen to me, and only once, is that I put a new battery in a vehicle and let it sit - with no charger/maintainer. Well, several months later, it started up just fine. I drove it throughout the day and with each start it had less cranking power. It then failed to start and the battery was toast. I wasn't surprised that sitting for several winter months ruined the battery but I was surprised it held a charge and started several times...but wouldn't take a charge. Seemed very odd to me.

robm2 said:

To test the alternator for a bad diode, measure the output for AC volts. If it is just one bad diode, the regulator can make up for it to a certain extent, so it will output what looks like the right DC voltage, but it will have lots of AC on it that the regulator and your DC meter can't see. Any more than about 50 mV AC is an indication of something wrong.

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Didn't know that. Will do. Thanks!

FletchMan said:

Ugh. The radio is aftermarket and I have a harness that fixed the battery drain problem when replacing stock...so I'm thinking there might be a short somewhere. I guess I'll try to remove the radio, first, and see if that's the culprit. If not, it has to be the wire somewhere...right?
The sunroof...maybe it's the module that has a problem. Guess it could be the wire, too.
Maybe I'll install a toggle switch for these two items and run it to the dash.

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Careful on the toggle switches - sunroof is directly controlled by the comfort module (CCM). Don't want to guess if that will cause different problems, possibly down the road after you have forgotten why...

I have had after market radios and their "adapter boxes" cause issues after a couple years. Might just be time for a new wiring adapter or radio.

Jason

With how they wired these cars, who knows what is really connected to what. I remember on my beetle, if a brake light was burned out, the cruise would not activate.