Help Needed: Electrical Drain on B7 A4

[RC52]

Hey All,

I'm trying my best to avoid a trip to a shop to hunt down the source of my electrical drain. I would really appreciate some help if anyone has seen an issue like this before. I'll do my best to concisely, but thoroughly, explain what is going on here.
My car's battery has been draining from full charge to no start in 2-3 days. When fully charged, the battery tests good as far as voltage while sitting, holding voltage while under starting load, and the alternator is putting about 14volts to the battery at idle as well. The battery is about 4 years old so I am fairly confident the battery and alternator are good.

A couple other things I've observed lately: The fuel pump doesn't prime when I open the door anymore but the car starts and drives just fine, the light that illuminates the window lock stays on ALL the time and so does the light that illuminates the headlight knob. Yes, the dome lights go out when I close the door and the alarm system arms so at least part of the car's brain knows that everything is closed, locked, etc.

In order to start testing the current draw on my car, I closed the drivers door latch and hood latch so the car thinks everything's closed and is willing to lock and arm the security system. Then, I waited for a bit (15-20mins) to let everything power down. Next, I used a multi-meter to test the current draw across the negative terminal connection to the battery. I connected the test leads and THEN disconnected the cable from the negative terminal of the battery to ensure power was not interrupted (I don't no if that is necessary but I didn't want any systems to "wake back up" once I reconnected the power through the multi-meter). The reading I was looking for was 50mA or less, based on several online sources. The reading I got was almost 1A (what?!).

My next step was to go through every single fuse in the fuse panel and check current draw across each circuit (by pulling the fuse and connecting the leads across the panel contacts). Most circuits were pulling single digit mA or fractions of mA.
Here is a list of the circuits that were pulling MUCH more than it seems they should when the car is off, locked, armed:
#1 (A/C) = 143mA
#13 (Steering Column) = 52mA
#15 (Instruments) = 240mA
#17 (Level, Tire Pressure Control) = Fluctuating from 32-75mA every 10sec or so.
#22 (Front Doors) = 32mA
#23 (Rear Doors) = 20mA
#24 & #38 (Central Comfort Electronics) = If both are unplugged I'm reading about 70-80mA across each, with only 1 unplugged I'm reading about 20-30mA.
#39 (Radio) = 71mA

Lastly, no codes on the OBDII system.

I hope this info is enough to cause a 'light bulb' for someone out there. I REALLY don't want to take my car in so someone can charge me hourly for their wild goose chase.

Thanks!
Pete

[Okedokey]

600mA @ 12V is 7W which is really nothing to worry about. Are you sure your voltage regulator and gen is working?

[mtroxel]

Okeydokey I think you're reading him wrong.

The reading I was looking for was 50mA or less, based on several online sources. The reading I got was almost 1A (what?!).

Mine pulls 300 mA after all has calmed down. It shoots up to 600 mA if I leave a USB charger plugged into a cigarette lighter. 1 A will drain you down.

I had a BMW with a parasitic draw. Pulled 1.5 amps after it went to sleep, and the damn thing didn't go to sleep till 14 1/2 minutes after you close all the doors. Put my mulita meter between the nag cable and the battery, removed half the fuses, waited 14 1/2 minutes. Still had the 1.5 A draw so removed half of those, etc. It was a puddle light in a door that never turned off. I just took out the bulb.

[RC52]

Thanks for the feedback, guys.

Okeydokey, it's pulling a little over 700mA in total. While that's not a huge number it's still enough to kill the battery if it sits for 3 days. Yes, I'm pretty certain my alternator is working correctly (unless it's got a bad diode or something that would cause it to draw from the battery when car is off) as it's supplying about 14v when car is running and I only have issues starting if the car sits for 2-3 days. Not sure about the voltage reg but I would assume it's okay since I'm getting a steady 14v at the battery when car is running.

mtroxel, I wish I could narrow it down to one circuit but I'm seeing a fairly high draw from several different circuits, as you can see.

Could this issue be caused by a faulty BCM (Body Control Module) or CCM (Comfort Control Module)?
I've heard that a BCM on the fritz can make random lights/system turn on or stay awake when your car is off. Anyone have any experience with such things?

Thanks!
Pete

[mtroxel]

mtroxel, I wish I could narrow it down to one circuit but I'm seeing a fairly high d<script id="gpt-impl-0.06950668104312185" src="http://partner.googleadservices.com/gpt/pubads_impl_92.js"></script>raw from several different circuits, as you can see.

Yea you're right. If mine pulls 300mA, it's sure not pulling 143 from the A/C and 240 from the inst cluster. I just don't know what all those individual circuits should pull but you're right, several look pretty needy. A couple thoughts:

1. The CCM is under the driver's seat and some guys have had water under there. Same quetion about the relays under the ECM. Some guys have seen water pooling under there.
2. When I do that test, I remove the neg cable, then put the meter between the battery and neg cable . That wakes the car, and I can watch it go to sleep. If I recall correctly, it takes this car about 1 1/2 minutes for all modules to go to sleep. It might be interesting to confirm that all your modules go to sleep. It might be anouther clue.

[RC52]

Yea you're right. If mine pulls 300mA, it's sure not pulling 143 from the A/C and 240 from the inst cluster. I just don't know what all those individual circuits should pull but you're right, several look pretty needy. A couple thoughts:

1. The CCM is under the driver's seat and some guys have had water under there. Same quetion about the relays under the ECM. Some guys have seen water pooling under there.
2. When I do that test, I remove the neg cable, then put the meter between the battery and neg cable . That wakes the car, and I can watch it go to sleep. If I recall correctly, it takes this car about 1 1/2 minutes for all modules to go to sleep. It might be interesting to confirm that all your modules go to sleep. It might be anouther clue.

Thanks for the info! I haven't specifically checked on the wake-up current draw vs. asleep so maybe I will try that tonight. Do you know roughly where the current draw is right when it wakes up? That would be another data point I could check against.

[mtroxel]

Thanks for the info! I haven't specifically checked on the wake-up current draw vs. asleep so maybe I will try that tonight. Do you know roughly where the current draw is right when it wakes up? That would be another data point I could check against.

I don't remember. It's been a while since I fooled with that on my B7. All I remember is that after putting the meter between the - battery and the cable, I was over 1,000mA for about 90 seconds, then it drops to 300mA.....all at once or in stages? I don't remember that either.

[RC52]

I don't remember. It's been a while since I fooled with that on my B7. All I remember is that after putting the meter between the - battery and the cable, I was over 1,000mA for about 90 seconds, then it drops to 300mA.....all at once or in stages? I don't remember that either.

Good to know. That should help. Thanks!
Going to do a little more research on the CCM as well. Seems that has been an issue for several people out there.

[RC52]

Update for anyone following this looking for their opportunity to help.

I checked my current draw when the car is unlocked and 'awake' vs. locked and 'alseep'. It looks like the car is pulling about 1.5A when it's awake and it settles around 870mA when it powers down and goes to sleep. Still way too high.

I also pulled up the carpet and checked the body control module in the driver's(front left) foot well. I saw what looked like crusty salt in a couple spots at the bottom of the cavity but no moisture and no sign of moisture or corrosion inside of the box where the module sits. I'm banking that it's okay.

I also did another check of the alternator, this time unplugging the connector on the back of the unit as well as disconnecting the large black wire that's fastened with a nut. The current draw did not change.

What the heck is going on here?!

[mtroxel]

Yea 870mA is pretty high. Is anything plugged in? I know if I leave a USB charger plugged into the cig lighter my draw doubles.

[RC52]

Yea 870mA is pretty high. Is anything plugged in? I know if I leave a USB charger plugged into the cig lighter my draw doubles.

Nope, nothing plugged into outlets. I also checked them, didn't see anything in there that would cause a short. Also removed iPod from dock in glove box - no change.

[mtroxel]

I forgot, it's not just a parasitic draw but also some flakiness with the door lock LED etc. Can't help but wish you could put VCDS on it. Bet one of those modules (comfort and convenience?) is throwing lots of errors.

[RC52]

I forgot, it's not just a parasitic draw but also some flakiness with the door lock LED etc. Can't help but wish you could put VCDS on it. Bet one of those modules (comfort and convenience?) is throwing lots of errors.

That's my next step I think. I'll need to take it to a local shop that does VAG stuff and have them scan it. I sure hope that uncovers some clues.

[mtroxel]

Where do you live in 'sconi? I'll be in parts of WI next week.

[RC52]

Where do you live in 'sconi? I'll be in parts of WI next week.

Just outside of Milwaukee. Wrong side of the state if you're not venturing far.

[mtroxel]

Just outside of Milwaukee. Wrong side of the state if you're not venturing far.

Yea I won't get east of Westfield (pop 900). It's on I 39 north of Portage.

[RC52]

Yea I won't get east of Westfield (pop 900). It's on I 39 north of Portage.

I should be able to find an independent shop that will give me a hand with the scan. I just hope I find something useful if I'm paying for it.
Thanks for the thought, though!

[canadianA4B7]

I've read first post a few times it reads like your using the oarasitic test method correct? just trying to confirm. Another quick thing is to just tighten down the ground screws. A loose one can cause this too and since its furthest from power and possibly only intermittent can screw the system. I found this out on my old allroad, the screw under the coolant tank had become loose and was draining mine the same as your description.

Just silly things to watch
-Interior light switch. (Switches can be bad and make contact inside which might be why you have units remaining lit when car off)
-Mice are assholes, I've seen them eat sheething off of 14/2 wire live 120vac never grounding the system and eating over 2 feet of the insulation
-silly but some add a grounding strap temporarily if you ground the system over a 3 day period and you show no issues upon start up you can confirm contact between 12 and ground. This worked well on old cars/trucks. Now with new technology I dont know. But a piece of wire from batt lead neg to the earth or from a know ground wire screw to earth cud help. It's ugly I get that but for diagnosis it cud help. (My theory cud be wrong I'll confirm with colleague on shift change)

[Okedokey]

Pull fuses until the draw is detected. Then investigate that circuit.

[RC52]

I've read first post a few times it reads like your using the oarasitic test method correct? just trying to confirm. Another quick thing is to just tighten down the ground screws. A loose one can cause this too and since its furthest from power and possibly only intermittent can screw the system. I found this out on my old allroad, the screw under the coolant tank had become loose and was draining mine the same as your description.

Just silly things to watch
-Interior light switch. (Switches can be bad and make contact inside which might be why you have units remaining lit when car off)
-Mice are assholes, I've seen them eat sheething off of 14/2 wire live 120vac never grounding the system and eating over 2 feet of the insulation
-silly but some add a grounding strap temporarily if you ground the system over a 3 day period and you show no issues upon start up you can confirm contact between 12 and ground. This worked well on old cars/trucks. Now with new technology I dont know. But a piece of wire from batt lead neg to the earth or from a know ground wire screw to earth cud help. It's ugly I get that but for diagnosis it cud help. (My theory cud be wrong I'll confirm with colleague on shift change)

I haven't looked into grounding issues yet. I'll try running a jumper cable from the neg. terminal to another spot on the frame and see if anything changes.
I've flipped just about every switch in the car just to see if something was stuck. Didn't find anything and I guess I can't see why so many circuits would be active if it's just a light switch malfunction.
Thanks for the suggestions!

- - - Updated - - -

Pull fuses until the draw is detected. Then investigate that circuit.

I've already determined that several circuits are drawing too much. The problem is figuring out why...

[RC52]

Update for anyone willing to wrack their brains and help me out:
I had a local shop do a full VCDS fault scan and he came up with several fault codes but couldn't make sense of them. The summary of all the codes is below. Anyone have any clever ideas? Anything look familiar??

AUDI A4 VCDS FAULT SUMMARY:

================================================== ========================
Address 08: Auto HVAC Labels: 8E0-820-043.lbl
Part No: 8E0 820 043 BM
Component: A4 Klimaautomat 3233
Coding: 00000
Shop #: WSC 00000
VCID: 6DDBB63C2709FF2A6F-515A

1 Fault Found:
00716 - Air recirculation Flap Positioning Motor (V113)
41-00 - Blocked or No Voltage
================================================== ========================
Address 15: Airbags Labels: 8E0-959-655-94.lbl
Part No SW: 8E0 959 655 M HW: 8E0 959 655 M
Component: Airbag 9.41 H01 4240
Revision: 91H01424 Serial number: 003CS0000AFP
Coding: 0032607
Shop #: WSC 06335 000 00000
VCID: 41833A8C1811CB4AFB-8014

Subsystem 1 - Part No: 8E0 910 339 D
Component: BF-Gewichtsens. H03 0080

Subsystem 2 - Serial number: 01HWY

Subsystem 3 - Serial number: 0001.01.0000H0300000000000ÿ†63

Subsystem 4 - Serial number: 000000ÿ†6332DRB406244CB5Rÿ†63

Subsystem 5 - Serial number: 44CB5Rÿ†6342DRB40625121EFÿ†63

Subsystem 6 - Serial number: 5121EFÿ†6352ARB403265B17Hÿ†63

Subsystem 7 - Serial number: 65B17Hÿ†6362ARB4032B55FF$ÿ†63

Subsystem 8 - Serial number: B55FF$ÿ†63729RB402B98B4D+ÿ†63

Subsystem 9 - Serial number: 98B4D+ÿ†63829RB402B98BA4$ÿ

Subsystem 10 - Serial number: 98BA4$ÿ

1 Fault Found:
00532 - Supply Voltage B+
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 2
Fault Frequency: 1
Reset counter: 39
Time Indication: 0
================================================== ======================
Address 16: Steering wheel Labels: 8E0-953-549.lbl
Control Module Part Number: 8E0 953 549 Q
Component and/or Version: Lenksáulenmodul 0801
Software Coding: 02041
Work Shop Code: WSC 06335
VCID: 41833A8C4B11CB4AFB-4B32
2 Faults Found:

01334 - Door Control Module; Rear Right (J389)
49-10 - No Communications - Intermittent
01332 - Door Control Module; Passenger Side (J387)
49-10 - No Communications - Intermittent
================================================== ======================
Address 17: Instruments Labels: 8E0-920-9xx-8EC.lbl
Control Module Part Number: 8E0 920 951 N HW: 8E0 920 951 N
Component and/or Version: KOMBI+WFS 4 H14 0200
Software Coding: 0023268
Work Shop Code: WSC 02609 444 59115
VCID: 356B5E5C5FD977EA57-5178
1 Fault Found:

00668 - Supply Voltage Terminal 30
002 - Lower Limit Exceeded - Intermittent
================================================== =========================
Address 46: Central Conv. Labels: 8E0-959-433-MAX.lbl
Control Module Part Number: 8E0 959 433 CP
Component and/or Version: Komfortgerát T7B 4336
Software Coding: 11820
Work Shop Code: WSC 06335
Additional Info: 8E1959801G Tõrsteuer.FS BRM 0706
Additional Info: 8E1959802G Tõrsteuer.BF BRM 0706
Additional Info: 8E0959801E Tõrsteuer.HL BRM 0606
Additional Info: 8E0959802E Tõrsteuer.HR BRM 0606
VCID: 0103FA8C0B910B4ABB-4B32
8 Faults Found:

01330 - Central Control Module for Central Convenience (J393)
52-10 - Supply Voltage Too High - Intermittent
01330 - Central Control Module for Central Convenience (J393)
53-10 - Supply Voltage Too Low - Intermittent
00962 - Alarm via. Tilt Sensor
35-00 - -
01368 - Alarm triggered by Luggage Compartment Switch
35-00 - -
01369 - Alarm triggered by Hood Switch
35-00 - -
01374 - Alarm triggered by Terminal 15
35-00 - -
01371 - Alarm triggered by Door Contact Switch; Driver's Side
35-00 - -
01561 - Rear left door
57-10 - Electric Circuit Failure - Intermittent

Thanks in advance!!!

[mtroxel]

I would say most of that is caused by:

1. Your low battery voltage problem.
2. Broken wires in door and trunk lid hinge points. Common problem on the B7.

And I'd say the broken wires in the hinge points might also be the source of your parasitic drain.

[RC52]

I would say most of that is caused by:

1. Your low battery voltage problem.
2. Broken wires in door and trunk lid hinge points. Common problem on the B7.

And I'd say the broken wires in the hinge points might also be the source of your parasitic drain.

I agree, think most, if not all, those codes are simply caused by the battery being dead/low. I also confirm that me air recirc flap isn't functioning, so that explains that code.
I checked the driver's and front passenger's door wiring at the hinge and it all looks fine.
I've looked at battery grounds and tried running a jumper cable in parallel with the grounds (battery to frame, frame to engine, battery to engine) to see if they were causing my drain issue. No change in current draw.
Has anyone checked their positive cable resistance? Where does the positive cable connect to the car? I would like to try this tonight. (I searched the forum a bit but didn't see much about the specific routing of the cable or how to access the car connection point). Is it in the ECU box that is a PITA to access?

Thanks!
Pete

[mtroxel]

Has anyone checked their positive cable resistance? Where does the positive cable connect to the car? I would like to try this tonight.

Mine pulls 300 mA after all has calmed down. It shoots up to 600 mA if I leave a USB charger plugged into a cigarette lighter.

RC you have a parasitic draw. The things you are doing so far may, or many not, narrow you down to the issue. The method to diagnose a parasitic draw has been established for years. Read this:

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Set up their test and pull fuses till the draw drops to 300 mA after the modules go to sleep. I recall it takes about a minute.

[Axis]

^^ thats how its done and you really have to wait a minute per fuse. Its worthless if you dont

[RC52]

RC you have a parasitic draw. The things you are doing so far may, or many not, narrow you down to the issue. The method to diagnose a parasitic draw has been established for years. Read this:

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Set up their test and pull fuses till the draw drops to 300 mA after the modules go to sleep. I recall it takes about a minute.

^^ thats how its done and you really have to wait a minute per fuse. Its worthless if you dont

Ah, I see what you're getting at. I didn't wait that long for each fuse circuit test (was testing current draw at the fuse panel for each circuit separately, not testing total current draw at the battery). Will do that when I have some time to dig back into it.

Thanks!
Pete

[mtroxel]

Ah, I see what you're getting at. I didn't wait that long for each fuse circuit test (was testing current draw at the fuse panel for each circuit separately, not testing total current draw at the battery). Will do that when I have some time to dig back into it.

I used that method on a 96 740i that would drain a new battery overnight. That %$#@! car had to sit for 15 1/2 minutes before it would go to sleep. Battery is in the trunk and it would not go to sleep with the trunk open. So snaked wires from battery to rear bumper, closed the trunk lid, pulled half the fuses, waited 15 1/2 minutes, blah, blah, blah.

I got the bastard though.

[RC52]

RC you have a parasitic draw. The things you are doing so far may, or many not, narrow you down to the issue. The method to diagnose a parasitic draw has been established for years. Read this:

http://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Set up their test and pull fuses till the draw drops to 300 mA after the modules go to sleep. I recall it takes about a minute.

^^ thats how its done and you really have to wait a minute per fuse. Its worthless if you dont

I used that method on a 96 740i that would drain a new battery overnight. That %$#@! car had to sit for 15 1/2 minutes before it would go to sleep. Battery is in the trunk and it would not go to sleep with the trunk open. So snaked wires from battery to rear bumper, closed the trunk lid, pulled half the fuses, waited 15 1/2 minutes, blah, blah, blah.

I got the bastard though.

I was able to flip the door and hood latches closed so the car would go to sleep with both open. At that point, I just pulled fuses and checked current draw across each. Made it pretty easy but I didn't wait that long while testing each circuit because I figured the car was still asleep.
Turns out when you pull the central comfort electronics fuse while the car is armed it triggers the alarm...
When I tested the draw at the battery I made sure to get the multi-meter hooked up to the negative cable and negative terminal before pulling the cable off. That way the car stays asleep because I didn't break the circuit, just transitioned it to go through the meter.

Back to the grind...

[RC52]

BIG NEWS!
It seems that my issue was all down to bad connections on the positive side of the battery.
In short, I disassembled the positive cable connections at the battery terminal (including the strip fuse), cleaned them all with a wire brush, put dielectric grease all over everything and reassembled. Somehow that's seemed to have fixed it! Now my current drain drops from 900mA to about 80mA after 30-45secs.
Note: I checked resistance across the positive wires and didn't come to any conclusions from that. Still seems that there was a bad connection, though.

1 Remaining Question for Anyone Reading This:
Does your headlight knob and window lock button stay illuminated after you lock your car? For about 30-45sec before finally going out? Those lights were staying on constantly before, now they go out after 30-45sec. Is that normal or is something weird still going on here?

Thanks! I appreciate the support from those who have chimed in. I hope that me closing the loop on this will help someone out in the future!

-Pete

[mtroxel]

Nicely done Pete!

1 Remaining Question for Anyone Reading This:
Does your headlight knob and window lock button stay illuminated after you lock your car? For about 30-45sec before finally going out? Those lights were staying on constantly before, now they go out after 30-45sec. Is that normal or is something weird still going on here?

Yes. Normal.

[RC52]

Yes. Normal.

Hmm...very interesting. That's kinda weird that those two, seemingly random lights remain lit for a short time. It's a good piece to the puzzle and should indicate what systems were staying awake, I just don't have enough info to figure that out right now. Although, I am much less concerned now that I'm back to normal again.