Hello,

First time poster, and I just want to say a quick thank-you to all the knowledgable members here who have saved me a lot of money over the years. Once my current saga is resolved, I'll post a longer writeup to detail the trials and errors of this issue, and hopefully return the favor a bit. Here's a shortened version. (The car is a 2001 A6 2.7T Quattro.)

I've been struggling with a parasitic drain for some months. Over this period of time, I've fixed a handful of problems that could have been related (old battery, failing alternator, broken driver's door microswitch), but not solved the drain. Once I found the time, I hooked up a multimeter to try to identify the cause. At first, the multimeter showed a normal draw of ~60mA. It was only when I figured out I really had to trick the car into thinking it was shut down, closed, and locked normally that the drain showed itself. Among other things, the key here was keeping power flowing when hooking up the multimeter by using a jumper cable to connect the battery cable with the negative battery terminal. This way, the modules never lost power, and I then got a draw of 250mA. I pulled fuses, and the draw dropped back to 60mA when I pulled the "Central Locking" fuse. For the past month or so, I've just kept the fuse pulled when parked, and the drain problem is gone. Of course, I'd like that circuit operational, so now I need to identify what's causing the drain.

My thinking it that it's the CCM, for a few reasons:

1) Around the time the drain started, I got a bad flood in the car courtesy of a clogged sunroof drain during a major storm. My TCM was out of commission for a few days, until I dried it out. So, the CCM could have flooded too.

2) Once I learned that the Central Locking circuit contained the CCM, interior lights, locks, alarm, etc., I suspected the CCM because some other parts of this circuit have been doing weird things. For one, my interior light would turn on at random times, or occasionally not turn off at shutdown. (I initially thought this could be the cause of the drain, so I flipped the switch to full off, and the light never came on again, but the drain didn't stop.) Additionally, Vag-Com (full error code readout below) does not register when the interior light is turned on. Also, occasionally my locks would act up, either by not unlocking remotely, or by locking themselves. This led me to believe the CCM may be acting up and doing funny things to other devices on the circuit.

3) I suspected the module because of my difficulty drawing out the parasitic drain in the first place. When I disconnected the battery before hooking up the multimeter, and thus powered off the modules, I got no abnormal drain. But when I kept power flowing to the system when hooking up the multimeter, the drain appeared. So, in other words, the drain is dependent on the CCM staying powered up after turning the car off. This suggests the CCM is playing a role in this.

So I pulled the CCM, and now I have doubts. The thing looks like it came out of the factory this morning. The protective box it sits in was tightly sealed and in great condition. The wiring and harnesses have zero damage or corrosion. The white sticker on the module shows no signs of any water stain. (The only thing I haven't done is opened the module itself to look at the circuit boards.)

So, before I go out and buy a used CCM, I was hoping someone with some experience with this electrical circuit (of which I have little knowledge, which may be obvious at this point) could shed some insight onto what may be happening. Does this sound like a CCM acting up? Could my CCM be water damaged even if it's in pristine shape? Would a CCM act up like this without some sort of damage? Or could the problem lie elsewhere in the circuit (say with that interior light wiring) but still be dependent on the CCM staying powered to actually draw the extra current?

Thanks so much for your help.

Vag-Com readout below. (Additionally, as mentioned above, the module is not signaling to Vag-Com when the interior light is turned on.)
-------------------------
Chassis Type: 4B (4B - Audi A6/S6/RS6/allroad C5 (1998 > 2005))

Scan: 01 02 03 06 08 15 16 17 18 22 34 35 36 37 45 55 56 57 65 67

75 76 77



VIN: WAUED64B61N148308

-------------------------------------------------------------------------------

Address 01: Engine Labels: 078-907-551-AZA.lbl

Part No: 4B0 907 551 T

Component: 2.7l V6/5VT G 0002

Coding: 06752

Shop #: WSC 02325

VCID: 3537DCC4EC5A44CF91E-513C

WAUED64B61N148308 AUZ7Z0A1830933



No fault code found.

Readiness: 0000 0001



-------------------------------------------------------------------------------

Address 02: Auto Trans Labels: 01V-927-156.lbl

Part No: 4B0 927 156 DJ

Component: AG5 01V 2.7l5VT USA 1717

Coding: 00002

Shop #: WSC 00000

VCID: 72BD27D8DDB413F774C-513C



No fault code found.



-------------------------------------------------------------------------------

Address 03: ABS Brakes Labels: 8D0-907-389.lbl

Part No: 8D0 907 389 E

Component: ABS/ESP allrad D56

Coding: 06397

Shop #: WSC 02325

VCID: 3537DCC4EC5A44CF91E-5160



No fault code found.



-------------------------------------------------------------------------------

Address 06: Seat Mem. Pass Labels: None

Part No: 4B0 959 760 C

Component: Sitzmemory R1 BF 0102

Coding: 00003

Shop #: WSC 00000

VCID: 2D07F4A4040A0C0FE9E-4B00



No fault code found.



-------------------------------------------------------------------------------

Address 08: Auto HVAC Labels: 4B0-820-043-MY1.lbl

Part No: 4B0 820 043 AH

Component: A6-Klimavollautomat D65

Coding: 00160

Shop #: WSC 02325

VCID: 60995D9003589167128-259E



1 Fault Found:

01841 - Potentiometer/Actuator for Temperature Flap; Left (G220)

30-10 - Open or Short to Plus - Intermittent



-------------------------------------------------------------------------------

Address 15: Airbags Labels: 4B0-959-655-AI8.lbl

Part No: 4B0 959 655 F

Component: Airbag Front+Kopf 2002

Coding: 00307

Shop #: WSC 02325

VCID: 3333E2DCE22E5AFFBFA-513C



No fault code found.



-------------------------------------------------------------------------------

Address 17: Instruments Labels: 4B0-920-xxx-17.lbl

Part No: 4B0 920 981 G

Component: C5-KOMBIINSTR. VDO D12

Coding: 02264

Shop #: WSC 01993

VCID: 2A0DFFB835E41B370CC-513C

WAUED64B61N148308 AUZ7Z0A1830933



No fault code found.



-------------------------------------------------------------------------------

Address 35: Centr. Locks Labels:. 4B0-962-258.lbl

Part No: 4B0 962 258 J

Component: Central Lock/Alarm D34

Coding: 15885

Shop #: WSC 02325

VCID: 3039EDD0133861E7C28-4F2E



2 Faults Found:

01561 - Rear left door

59-00 - Can't Unlock

01562 - Rear right door

59-00 - Can't Unlock



-------------------------------------------------------------------------------

Address 36: Seat Mem. Drvr Labels: None

Part No: 4B0 959 760 B

Component: Sitzmemory R1 F 0101

Coding: 00001

Shop #: WSC 00000

VCID: 2C01F9A03F100507FE0-4B00



2 Faults Found:

00668 - Supply Voltage Terminal 30

07-10 - Signal too Low - Intermittent

00668 - Supply Voltage Terminal 30

06-10 - Signal too High - Intermittent



-------------------------------------------------------------------------------

Address 45: Inter. Monitor Labels: 4B0-951-178.lbl

Part No: 4B0 951 178 A

Component: Innenraumueberw. D04

Coding: 00101

Shop #: WSC 02325

VCID: 26150B8821FC3F57284-50AE



2 Faults Found:

01349 - Alarm via Theft Warning System; Front

35-00 - -

01462 - Anti-theft alarm ultra sonic Sensor (G209)

53-10 - Supply Voltage Too Low - Intermittent



-------------------------------------------------------------------------------

Address 56: Radio Labels: 8D0-035-1xx-56.lbl

Part No: 4B0 035 195 A

Component: Radio D00

Coding: 00201

Shop #: WSC 00003

VCID: 1E65236879ACE797604-4B7A



No fault code found.



End----------(Elapsed Time: 04:53, VBatt start/end: 14.1V/13.8V)-----

 

Check the function of the door lock actuator switches.

Watch this video...

 

@georgeb944 Thanks very much for the tips.

I put your suggestions to use this morning, and now I'm more confused than before. Employing the drain test from the video (voltage drop at the fuse), I was getting no voltage drop over the Central Locking circuit. So the question now is has the problem fixed itself (perhaps just unplugging and replugging the CCM did it?), or does this test not pick up on something that the amp test does?

I tested the actuator switches--all the doors and trunk locked and unlocked properly, and the car did indicate when the doors were open, so it seems the switches are working properly. Is there anything else I should look for there? The only thing I noticed was that I didn't get a hood open warning light. But it strikes me that this isn't associated with the drain, because when I got the 250mA draw, the harness at the hood was unplugged.

The dome light remained bizarre. When I first prepped the car for the test, the light stayed on after locking. So I manually shut it off (because I was still getting the drain with it manually shut off). When I came back and ran the test, I tried the light out again by flipping it into auto mode, and it was working perfectly. I'm going to keep playing with it to see if I can figure out any pattern as to when it does and doesn't work.

Thanks again.

 

I have this same problem. water hasn't made its way into the footwells completely, but I have found that my module right above footwell on the drivers' side did indeed have water damage on the circuit board. I thought it could be a faulty design with the windshield plenum draining system, but those seemed good and checked out. I haven't checked my sunroof drains, I'll do that next time I get a chance. BTW I have a 2010 audi a4

 

You might get more responses if you post your question in the right forum.

this is the discussion forum for the C5 Audi A6 and S6 produced from 1998-2004