Another drama, 6 hour wait for the AA, massive power drain?

The clamp / loop type meters are better than the normal one where you have to connect it in series. Full power can still flow through the wiring and this is sensed by the loop and not limited to the wire thickness or fuse capacity of the meter.
 
It’s permanent……but it’s the dash cam, so itbwas my non eureka moment when I pulled it and made no difference 😨
 
I’m wondering about the radiator fan control, but having pulled the fuses I guest can’t be.
The thing that seems odd is the no coms with VCDS, it did used to as it identified the micro switch in the door and fuel cap issue.
 
Is the Alarm fused at the fuse box? Maybe not to stop thieves pulling the fuse to stop the alarm sounding. But then there ought to be an in-line fuse,

Has the A2 got a tracker device that you are not aware of that could be now malfuntioning and draining the battery. Again it might not go through the fuse box.

Just ideas Drew. I hope you find the problem soon.
 
PlasticMac said:
Instead of thinking electrics, think water, header tank in the loft.
The height of the tank is pressure, (= voltage).
The size of the pipe is the flow rate, (= current).
The size of the tank is capacity, (= battery Amp hours, Ah)
So our tank is in a bungalow, so the pressure, (= voltage) is quite low at 12 volts.
The apparent high current drain, (large pipe/big leak), means the header tank, (battery), is emptying quickly.
So, you're looking for a big leak, because all the taps are off, but the tank is still emptying, and wherever it's flowing will get very wet if it was water, (or hot with electricity).
As an example, both headlights on will draw about 10 amps.
Finding the problem will be a process of elimination. The alternator is an obvious suspect, as it contains components that should only allow high current, (to charge the battery), to flow out of it, but a failed one can allow current, (our leak), to flow in too.
Mac.
Click to expand...
OK, so having eliminated the alternator. Next, let's eliminate the starter. Again, disconnect the battery, remove the big black wire from the starter, and cover it to prevent contact with anything else.
Reconnect the battery, and check current.
Mac.
Please see next post.
 
Last edited:
I'm a bit busy this morning, so, if the starter is eliminated, the next move is to remove fuse 88, the strip fuse on the battery positive connection. Usual precautions.
If it's easier, you can disconnect the starter there too.
Mac.
Edit: In fact, if you remove fuse 88 first, and connect your meter across where it was, (maybe fix the leads under the retaining nuts), and you still see 5 amps, then the current is being drawn by the car's electrical system.
(If no current, then it's starter, alternator or power steering, the only things before fuse 88).
The cable going away from fuse 88, goes to the main fuses, both the fuse panel, and the under floor.
I'd remove fuses, one by one, (and don't replace them), until the current drops 🤞
Mac
 
Last edited:
PlasticMac said:
I'm a bit busy this morning, so, if the starter is eliminated, the next move is to remove fuse 88, the strip fuse on the battery positive connection. Usual precautions.
If it's easier, you can disconnect the starter there too.
Mac.
Edit: In fact, if you remove fuse 88 first, and connect your meter across where it was, (maybe fix the leads under the retaining nuts), and you still see 5 amps, then the current is being drawn by the car's electrical system.
(If no current, then it's starter, alternator or power steering, the only things before fuse 88).
The cable going away from fuse 88, goes to the main fuses, both the fuse panel, and the under floor.
I'd remove fuses, one by one, (and don't replace them), until the current drops 🤞
Mac
Click to expand...
That a really good suggestion, thanks. I’d not thought about the starter or power steering, I’m sure I’ll find it, and better to be a 5 amp draw than a 1 amp as it should be very obvious……when I find it that is!
 
Ok…..so I has a few hours on it again today, I tried disconnecting the main fuse as suggested, and I concluded it’s definitely not the alternator, starter or steering. I moved to the front where the main cable feeds into the ecu compartment under the passenger floor, and disconnected it and put the meter in line…..still pulling 5 amps.
next I started pulling fuses again, but this time I left each one out and placed on the floor, no change until I got to the saddle fuse for the dash cam, and realised there’s a 20 amp fuse underneath that wasn’t visible, pulled it and it dropped to 0.5 amps …EUREKA!!
The next part is a bit of a mystery as it seems a few things happened at once, and I’m not entirely sure what happened first. To try to figure out what the fuse I replaced all of the fuses and then tried everything on the car to see what didn’t work, and it was the fan control fuse ….aha! I replaced the fuse and switched on the air con as this usually kicks the fan in slow……it didn’t! I then got back in the car and realised the blower fan didn’t work either, even putting it onto full….aha! Back under the bonnet (on a normal car lol) to look at the cooing fan and the controller and saw that the pipes from the compressor, the accumulator and aluminium pipes to the bulkhead had completely frozen up, all within a couple of minutes!!
 

Attachments

  • IMG_3764.jpeg
    IMG_3764.jpeg
    2.7 MB · Views: 38
  • IMG_3766.jpeg
    IMG_3766.jpeg
    2.2 MB · Views: 36
  • IMG_3765.jpeg
    IMG_3765.jpeg
    1.3 MB · Views: 39
realising that something was getting too cold somehow, the cause was probably to do with both fans not working?
Engine off, I connected the meter again, still pulling 5 amps so I pulled the 2 big plugs on the fan control unit and it dropped….so even though it’s not working it’s using power, I then moved into the car to look at blower fan, glove box out and spin the fan with my fingers and it rotates easily, next I pull it’s plug and give it 12v to the fan, it works instantly.
I re connect the blower fan, and reconnect the fan controller, and check power draw…….its gone, back to 0.5 amps!?!
I start the engine, set the climate to 21, the blower starts working and the cooling fan also!!
so I’m a bit further ahead, but not entirely sure what’s at fault? Did the cooling fan keep running at the airport to flatten the battery? Seems feasible? Why did the blower fan not work? Is it possibly on its way out and a solid 12v to the motor kicked it into life, as opposed to the slow start the climate control gives it?
was there a dodgy connection within or around the fan control unit causing some short or power drain, seems unlikely??
I have no idea what happened, but at end of play it all seems to work with no power drain when switched off. I suspect it’s more than one thing, and more worryingly I haven’t found the issue so we can’t trust this car until it’s sorted.
My thought is it’s the fan controller as this seems to have constant power, and I assume it’s able to run after the ignition is off??

so….what do you think??
 
Drew. How about this post about an A4, maybe the A2 is similar.

Cooling fan running all the time... - AudiWorld Forums

A4 (B6 Platform) Discussion - Cooling fan running all the time... - Is this a common issue? I think it thinks its hot, so in the cold weather it starts hard and stumbles at first and the fan never shuts off. I logged a while ago and it said something about a electrically controlled thermostat...
www.audiworld.com

Besides the radiator fan coming on after the ignition is off, the post says the Auxiliary fan can as well. This is controlled by the A/C controller, used to cool the A/C condenser. If either fan controls malfunction and stay on then the result can be a flat battery.

And this A3 post

www.audi-sport.net

Aircon fan wont stop!

I have a '05 A3 3.2L quattro and yesterday the aircon fan started spinning and wont stop - even with the ignition off. I have tried various combinations of aircon settings and even tried removing fuses but it wont stop. If I leave the car for any length of time the batt is dead and I have to...
www.audi-sport.net www.audi-sport.net

mentions aircon fan staying on and flattening the battery and may be due to low pressure in the aircon system.
 
Last edited:
The radiator fan, and it's controller would be my prime suspects, as the fans can run when car is off, to clear residual heat.
Suggest a scan, and clear the DTCs, there'll be loads I think.
Then scan again after a few trips, to see if there's any clues.
The FCM could have a partial short, not enough to run the fan, but enough to give the 5 amps. When the cooling fan runs, it draws more than 5 amps.
I'd put an FCM by, as insurance.
Mac.
 
PlasticMac said:
The radiator fan, and it's controller would be my prime suspects, as the fans can run when car is off, to clear residual heat.
Suggest a scan, and clear the DTCs, there'll be loads I think.
Then scan again after a few trips, to see if there's any clues.
The FCM could have a partial short, not enough to run the fan, but enough to give the 5 amps. When the cooling fan runs, it draws more than 5 amps.
I'd put an FCM by, as insurance.
Mac.
Click to expand...
Yes, that’s what I’m thinking 😀
 
Thanks to Steve for getting a control unit to me, it’s now fitted and normality has been restored!
power drain has gone from 8.3a to a tiny 0.13a after it’s been locked for a while and its happy sleeping.
thanks for everyones input, it’s appreciated!
 

Attachments

  • IMG_3811.jpeg
    IMG_3811.jpeg
    1.9 MB · Views: 37
  • IMG_3812.jpeg
    IMG_3812.jpeg
    1.2 MB · Views: 37
You must log in or register to reply here.
Back
Top