Mysterious battery drain - 1.4A with car locked!

bentwenty

Registered User
A few weeks ago I fitted heated seats, while I was doing this I had the car open all day, so drained the battery. I jumped the car and all was well.

A few days later I came to it in the early morning for work and again it was dead, so I jumped it, and as soon as I got to work a bought a brand new battery (690A cold cranking current, 72Ah) to replace the 4 year old Bosh S3.

That was not the end of the story however, it refused to start this morning, a week after fitting the new battery. So I have spent the afternoon investigating. I have done the following:

The alternator runs at 14.4v, so it's not that.

I connected my multimeter (fused for 20A) in series with the earth terminal of the battery.
Once the car has been locked, the current settles down to a steady 1.4A, and stays there!
I have unplugged the fuse for the amps in the boot, not that, I have unplugged the heated seats (my first suspect), no change. I then went through both the engine bay and interior fuse boxes, unplugging and replacing them one by one, but no one fuse will make it drop below 1.2A.
I have heard stories about the alarm sounder, I replaced it with a second hand one about 8 months ago, the alarm is fully functional.

A few side notes: recently when I press the unlock button, the car seems to unlock (lights come one and I hear the lock solenoids), but sometimes I can't open the doors until it's been pressed again.

The only thing that I know of that stays on is the glove box light (due to a broken microswitch), but it's a 20mA LED.

I have a number of DTCs that I haven't been able to clear for about 8 months, they include intermittent faults for both rad fans, and implausible signal faults for both window winder regs. I will post he current DTCs when I scan to tomorrow.

Any input would be greatly appreciated! I am current carrying a spat battery in the boot, and it's getting a bit tiresome doing all the ABS sensor calibrations and output tests every time the battery dies!

Cheers, Ben
 

bentwenty

Registered User
Thanks, I'll try that later! I assume the alternator does not have a fuse, so disconnecting all the fuses would not have picked it up.
If it is at fault, I would expect the 1.4A current draw to disappear.

Ben
 

bentwenty

Registered User
That's a good point, thanks, I'll have plenty of electrical tape to hand when I do it.
I have the following codes (before clearing them):
9c0d53cc042609003758cf5edbfc29ac.jpg

58adb727d5bd0a3eb015fa94eea039ea.jpg

a2ecd695a7faccaff07b350ee8168516.jpg

b01ef5820b84c63e91e5d4fbe685f267.jpg

418ff4052aba768ca3a0abfc18f3381b.jpg


I assume a lot of those were caused by me playing with the fuses, they cleared to give these (with the engine running).

839901cce9b79b0d2c711e6b1c6e0d13.jpg

b44cd64ae4b84c92c2ea6304009ffda6.jpg

05db3a60d428b96651306c2863d0bc11.jpg


I don't know what to make of a lot of those, I'm having a bit of a nightmare with the car today, it's just developed an exhaust leak this morning. I think it's the (redundant) pipe that goes from the egr cooler to where the egr valve was, so I have to fix that as well.
:(
 

bentwenty

Registered User
The car has gotten worse again :(
The clutch has gone a bit soft, and the bite point is near the bottom, when I slightly touch the peddle, the hissing sound that I thought was an exhaust leak gets a lot louder.
The sound is only audible in the cabin under load, it's not a boost leak as it holds boost fine (according to boost gauge).
I can smell exhaust gas in the engine bay, and hear a steady hiss on idle from the egr cooler area :(
It's really not my day today...
 

bentwenty

Registered User
Yes, just remember there is a direct connection from the battery to the alternator so be careful when you remove the main power connection as if it grounds somewhere you will get some big sparks.


Karl.
Solved all the other issues yesterday, still got the battery drain. Disconnected the alternator but made no difference, I'm not sure where to go from here, the DTCs don't seem to reveal much :(
 

nluk100

Registered User
Try removing the radio fuse (usually located under the bonnet). This has been know to cause discharge issues on some VAG cars.
 

bentwenty

Registered User
Radio fuse (F19) made no difference, I've already been though both fuse boxes :(
Removing the bulb in the glovebox light dropped it from 1.4A to 1.2A, removing F24 (control unit for CAN gateway data transfer) drops it to 0.7A, I'm not sure what's going on!
 

bentwenty

Registered User
Getting to the point of giving up on this :( local Audi charge £110+VAT, so that's a no go, and my favourite VAG specialist can't get me in until next Thursday :(
 

bentwenty

Registered User
Could it be the battery?
Unfortunately not, I wish it could! It's a brand new battery (2 weeks old), and I've ruled it out in my original post as something is drawing current with the car locked.

I also found a removed this insurance tracking box, it must have been installed by the previous owner.
233330049e1541301cd248aa7d5b4fb6.jpg

Unfortunately it was drawing any current so it's not worked my problem :(
 

crazylegscrane

Registered User
Feel sorry for you as electrical problems are a pain with cars, Audi charge a lot and have a change a part and see if it fixed it attitude so can get expensive quickly.

Good auto electricians seem to be hard to find as well.

I have an intermittent electrical fault as well with mine and I'm still wondering who to go to with it
 

PaulRS3

Registered User
Is the drain only when locked?

Have you got a dodgy door lock solenoid that is staying on/ not getting a locked confirmation signal to turn off?

A few simple checks to see if internal lights go on/ off with doors opening and closing.

Similar is to arm and disarm alarm and open a door and wait 1min. Repeating for all doors.

If the alarm rearms and locks the car after a minute, it hasn't seen the door open, and thinks you have accidently unlocked the car, so will relock it.

I had a door lock micro switch play up on an 8L S3 this way, although didn't cause a battery issue.
 

bentwenty

Registered User
It draws the same locked an unlocked.
I know all the lights go off, I have checked them.
I will try with the alarm tomorrow. I have had the microswitch issue last year on it, replaced both locking modules.
As far as I can tell, Al the locking solenoids are working, and the alarm is arming properly.

I may have found something significant; when I pull this fuse, the current drops to 0.2A, which I think is normal, I think this fuse is just the main fuse for the fusebox, but could it be part of my answer? (The pis is not of my car, I'm using it only to illustrate the location)
d2a0c3d76c85c107a9e2175f2695e689.jpg
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
As close as I can see that fuse is only used if the car has doctor / police option or is used from may 2008 the electronically controlled damping control unit J250 and if so should be a 30A fuse.
What year is your car and does it have electronically controlled dampers ?
What year is your car ?
Seeing as it seems to be a spare in a lot of cars may have been used to feed something aftermarket.

Karl.
 

Sprinter2012

Registered User
Probably a stupid suggestion, but have you checked the boot light?

Could you lock the car without the parcel shelf or fold the seats down to see if it stays on?
 

bentwenty

Registered User
Probably a stupid suggestion, but have you checked the boot light?

Could you lock the car without the parcel shelf or fold the seats down to see if it stays on?
Yep check the boot light, it goes off :(
Also checked the red lights on the side of the doors and the puddle lights but closing the door lock with a screwdriver.
 

bentwenty

Registered User
What year is your car ? If you disconnect that feed what stops working. ?
Sorry, didn't see your first reply!
Its a 2003 A3 2.0 TDi, I think the fuse was 50A, when I pulled it, I think everything stopped working, but it was hard to tell as the remote locking wouldn't work with it pulled.
I'll get a picture of mine tomorrow, I'm sure it was identical to this one.
I can't think of anything aftermarket that may be using it, there are no parking sensors or anything like that, I've run my own fuses for all my mods.
It didn't have the fancy dampers and its on coil overs now...
Ben
 

bentwenty

Registered User
I was looking at a later car, they changed a lot in 2006.
could you take a picture of the actual box and note the values of the fuses across the front.
Also is your battery in the front or boot?

Sure, here is my bay
6fe04c6616b5c5a85727320f560136d9.jpg

Battery is in the front stock location
757f0285ef1d189f755c073dce098fbd.jpg

The fuses along the front (left to right from the front of the car) are 200A, 80A, 80A, blank, feed for 50A fuse for amps in the boot, 100A, incoming feed from battery, 80A.
303b9a00f470230d4e78b7c766407fc2.jpg

It's the 80A furthest on the left that drops the current to normal levels.

Ben
 

bentwenty

Registered User
Cheers I'll have a crack later, I haven't had any unexpected faults on that module. That said, are these faults normal every time the battery dies?
10b919640e9333a8b05946e3dd943c88.jpg

Presumably I'm looking at physical damage of some sort and also heat from the current draw?
Is it surprising that I wasn't able to use the central locking with that feed unplugged?
Many thanks
Ben
 

bentwenty

Registered User
These are the diagrams from Elsa Win that show the fuse locations are uses. I can't see any connection to the central locking from the steering rack controller.
Could be some water ingress into the module causing issues, check for damage and water on the connectors.

View attachment 47262

View attachment 47261

Karl
Awesome, thanks for those diagrams!
Unless I have missed something, it was no 9 I found to solve the problem not number 2, which would means it's the fuse for the window winder regulators.
I have had implausible signal codes on both door locking modules for 6 months, could it be related? I replaced them both which solved my problem, but I've never been able to clear the codes.
e81f6a96a42e5f37b98ec0b07a9e19ff.jpg
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
The S37 30A fuse that feeds the window wiper motors is located here.
Audi A3 2004 S37 fuse location.JPG

I would pull S37 to see if it clears the current draw. One of the guys at work had an issue with his central locking on an Audi TT and it turned out to be the wires braking down and shorting in the door shut. The garage that fixed it replaced the door loom on the drivers door.
Not sure if you could have a similar issue, maybe water damage in one of the doors or a faulty module.
If you are lucky you might get to fix a few faults in one go.

Karl.
 

bentwenty

Registered User
You said it was the 80A fuse furthest on the LEFT that is the 80A fuse that feeds the steering controller.
Do you mean the 80A fuse on the right ????
You are absolutely correct! I'm terribly sorry, I meant right! Not left!
 

bentwenty

Registered User
The S37 30A fuse that feeds the window wiper motors is located here.
View attachment 47276
I would pull S37 to see if it clears the current draw. One of the guys at work had an issue with his central locking on an Audi TT and it turned out to be the wires braking down and shorting in the door shut. The garage that fixed it replaced the door loom on the drivers door.
Not sure if you could have a similar issue, maybe water damage in one of the doors or a faulty module.
If you are lucky you might get to fix a few faults in one go.

Karl.
That sort of issue sounds entirely possibly in my situation, as you say, it could also sort out the other issues I'm having. The car is plenty old enough to have that sort of issue in the door boot.
I believe I already have water damage to one of my rather expensive aftermarket door speakers, so I'm starting to see a possible pattern...
Is S37 located under the steering wheel to the right, behind the cabin fuse box where the main loom comes from the scuttle to the cabin?
I'll pull that tomorrow and have a poke about in the door when I get a chance.
Cheers
Ben
 

oldoiler

Registered User
Sure, here is my bay
6fe04c6616b5c5a85727320f560136d9.jpg

Battery is in the front stock location
757f0285ef1d189f755c073dce098fbd.jpg

The fuses along the front (left to right from the front of the car) are 200A, 80A, 80A, blank, feed for 50A fuse for amps in the boot, 100A, incoming feed from battery, 80A.
303b9a00f470230d4e78b7c766407fc2.jpg

It's the 80A furthest on the left that drops the current to normal levels.

Ben
Where r u located, we r a vag independent in Wiltshire and our rates r half vag main dealers. ...
 

bentwenty

Registered User
According to Elsa Win it's on the LHS which would put it at the back or under the glovebox, it's located by several relays and the onboard supply control unit.

Karl.
I had a bit of a poke about last night, I have double checked that it is the 80A fuse for the window winder regulators. With it unplugged, it drops to this, which I believe is entirely normal.
eae96b69128ec1a1e9de4083cfb21c46.jpg


I can't seem to find the relays and fuses you mentioned tough, they are not behind the glovebox (it's a RHD car)
56102af5a409609cd1a9902b0cf63be0.jpg


And they are not behind the steering column
4c58ac77a801b96d61b72a1e187ebbc5.jpg


I suppose the next place to look is in the boot, although I don't remember bumping into anything like that when pottering about behind the panels to install my hidden sub.
Ben
 

bentwenty

Registered User
Hello,
I think nearly 300mA is high for standby current. Typically on most cars it's something like 50-100mA .
But it's a lot less than 1.4 A.
I believe this is the fuse highlighted with the arrows.

View attachment 47406
I have just tried pulling the highlighted fuse, I'm not sure if it is the right one. It is a 30A fuse, but it makes no difference to the current draw.
It's also worth noting that the central locking is fully functional without it.
I'm going to try opening up the doors and looking for anomalies.
Cheers
Ben
 

bentwenty

Registered User
I can't see any signs of wiring damage in the drivers side, unplugging all the wiring to the regulator makes to difference either.
c99b4ea562a9d936f47be10617d7a52e.jpg

I'm moving on to the passenger side now
 

bentwenty

Registered User
Same story for the passenger side, I haven't been able to inspect the wiring through the boot its self as I'm jot able to disassemble it easily.
Unplugging all the modules makes no difference, so I can rule them out at least.
Not sure where to look from here.
 

desertstorm

Moderator
Staff member
Moderator
VCDS Map User
That 30A fuse provides power to the motors on the windows, If you had tried to operate the windows when it was removed they wouldn't have moved.
The other fuses fed by that 80A are in fuse box SC which is the one on the end of the dash panel.

Audi 2003 A3 fuse box SC.JPG


Fuses SC12 -SC17 and fuses SC 22- SC27
aUDI 2003 A3 fuses SC12 -SC27.JPG

I would pull all these fuses till you find the one causing the current draw.
My favourite would be SC17 for the CCM, that always seems to cause issues for people, On Passats anyway.

Karl.
 

bentwenty

Registered User
Awesome cheers!
I will have a go later tonight and see what I find.
In my initial go at a fault finding it last week, I did go through all the fuses in SC and don't remember seeing any drop in current.
However I will now be going back to it with fresh eyes and new information.
Cheers
Ben
 
Top