MK4 Electrical Problem

[MechEngg]

Hey guys,

Actually need help on this one. I have tried as much as me and my research could think of and i'm coming back blank.

Car sat over the winter, battery hooked up for the first few weeks probably before i disconnected (moving it around a few times) and it sat for 6 months(ish). Hooked up the battery and as predicted had to boost it to get it running. Had to keep boosting it to start it the next 5 or 6 times.

Bought a new AGM battery from Natty. Did not fix the problem.

Was still running into issues having to boost the car but the period was extended to every few days or a week when i actually hooked up a proper battery charger. My next thought is that my alternator wasn't charging the battery properly and only just keeping the car running. Also noticed that one time the car started to overheat from maybe the fans not kicking on when they are supposed to.

Borrowed alternator from Brent. Did not fix the problem.

So now i have to check for parasitic draws. Tested every fuse and no mA across the entire fuse block as per VW parasitic draw procedure. Next though is FCM or fans because i was having over heating issues. So i charged up the battery fully and left it unhooked for 3 days. Stayed at 12.46V the entire time. Hooked up the battery leads and pulled the cables for the FCM and the 3 30A fuses for fuel pump and large fans and the SAI (deleted) and airride and let it sit for yet another 3 days.

Leads us to today.

Still at 12.45A which i though is acceptable. Popped fuses back in and it started right up. Great i though. Now plug the airride back in so i can remove front bumper to deal with fan issue. Fans have now tested out to be good in both low speed and high speed for each fan individually. With FCM plugged in thermoswitch works. Great i thought. Now i can take it for a test drive.

Dead.

I have now unplugged ONLY the airride and i'm charging just the battery with no leads attached to it.

Help/Thoughts on what i can do next or anything else to try. I don't know how just my airride controller (all compressors unplugged etc) could draw that much current even if it was shorted at all.

Thanks,
Sean

[Lars]

Re: MK4 Electrical Problem

Ya you'll have to isolate systems and see what's causing the draw are your controller and compressors linked to the same circuit or separate? Any sensors or what not ?

[stefan]

Re: MK4 Electrical Problem

Not sure how big the draw is, but if you ammeter can handle the draw (with car not running....), you can pull a battery terminal and but the ammeter inline between battery and battery cable. It will give you the draw, and a real-time result if you go pulling fuses/breaking circuits.

I have had luck with this, but the automatic draws like interior lights and potentially fuel pump that turns on when you open a door could be too much draw for a basic meter since at this point, your whole system is drawing through the inline meter, so take that stuff in to account or you will blow a fuse in your meter.

[kujiwara]

Re: MK4 Electrical Problem

I knew my door sensors used to drain my battery, but that's like parking the car for five days a week. Also this winter I found out that my rear defroster draws lots of power, my blue dash needles would be nearly colorless at night below 2000rpm with the rear defroster on. On top of that check if you ripped any wiring under the car while driving. Good luck!

[onceover]

Re: MK4 Electrical Problem

I've got a spare FCM if you would like to try it out