mkv gti battery drain

[antsaw]

Gday im new on here... just wanted to know if anyone has had trouble with getting a flat battery? Lastweek my thermo fans would turn on randomly after the engine was off. Sometimes hrs later! So after a week in the garage they replaced the sensor near the oil cooler, which has apparently fixed the fan problem, but this morning my battery was flat again. I made sure the fans didnt turn on cause i was monitoring it. So its got to be something else aswell. Two auto electritians ive taken it to have no idea what it is so im getting a bit over it!
Any info would be much appreciated!

[Umai Naa!!]

I would still keep the fans in mind.

There is an internal fault in the module that controls them (it's actually part of the fan assembly). This can sometimes short-out internally, causing the fans to run on, and drain the battery. I've also seen one where the fans weren't actually working, but the module was still pulling enough current to flatten the battery in a matter of hours.

Other things to consider are the condition of the alternator, any aftermarket or non-original accessories (the radio unit for instance; perhaps upgraded from the standard one?), and the condition of tha battery itself. Just on the alternator itself, the pulley has a one-way clutch on it, so-to-speak. Spin it one way, and the internals of the alternator will spin and charge the battery. The other direction will not. Occasionally, these fail to the point where neither direction will allow the alternator to charge the battery. Easy enough to test with the car off, and the belt removed, and locking up the alternator and testing which way the pulley spins. If it spins freely in both directions, it's no good.

For the DIY-ers, this method is the easiest, and least-intrusive way of testing on a modern vehicle:

A new approach to testing parasitic draw | Search Autoparts

And here's a link with charts that compliment the fuse you're testing, and the reading it should have:

Fuse Charts Download

[antsaw]

Awesome thanks for all that info. Youd think that an auto electritian would check all that aye. I do know that he had the new fan plugged in for a couple of hrs though. So im thinking its not the control module... i was driving through alot a deep puddles during the newcastle storms so might have somthing to do with that. Argh!

[antsaw]

Ok so the fans are still turning on in the middle of the night. After ive had a new coolant sensor put in. And plugged a new main fan in, which still came on. The only thing left is the thermostat sensor, but if that was reading a high temp, and turning the fans on, why doesnt it show on the dash??? Alternator is fine too. So is battery