GerryAttrick 1 Report post Posted January 6, 2009 For a while I have had an intermittant parasitic drain on my E39 Touring that frequently flattens the battery(s). I am now on my 3rd battery and until recently the cause had proved elusive. . As you probably know the BMW takes about 20 minutes for all the onboard elek-trickery to close down. You can verify this by the fact that the Park light on the transmission tunnel eventually goes out. However it is hard to find a drain as once you open the car to put a multimeter on everything wakes up and so you get a current draw again! Had the car at Official BMW agents (un-named) but they could not find the (intermittant) fault but said my new(3 week old) battery was faulty. After a check last night it turns out that the battery was NOT faulty - just down on power and after a run home was up to full strength. :banghead: After a bit of Googling and hunting E39 sites I had finally pinned my hopes on it being a common E39 fault - a faulty FSU (Final Stage Unit...or Blower Motor to the rest us mortals) resistor. Printed out the instructions with the plan being to attack the problem while at the beach for a spot of R & R. Just received a call from my wife, who is driving the car while her brother from Oz uses her 318ti, to give me a mixture of good news/Bad news. Bad news 1. She had arranged with BMW agent to install a NEW OEM Battery - cost nearly $500 fitted!!!!! Good news 1. Agents had found the parasitic drain - the FSU resistor Good news 2. I can say "I told you so". Bad news 2. She Ok'd the replacement at nearly another $500(the part is available on Ebay for $US70 approx) and it is less than an hour to fit although by all accounts a "baitch" to get at. Good news 3. I can now go on holiday and know the car is going to start when needed. Bad news 3. Keeping all the surplus batteries fully charged with my battery tender will probably cause Brown Outs over Auckland next winter. checks show that they are ALL OK - just drained by the frickin resistor Not sure if this is in the correct forum so Mods can move it is not...but if you are having an elusive parasitic drain on your E39 (and possibly other models) check the FSU resistor. probably just pulling the fuse (#76 )could be a starter to see if the drain still happens. Oh...and if anyone wants a good non OEM Battery at around the $100 mark pm me Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted January 6, 2009 Thats quite a common fault Quote Share this post Link to post Share on other sites
GerryAttrick 1 Report post Posted January 6, 2009 Thats quite a common faultI agree...its more than a little annoying that I couldfinally track it down and yet the BMW agents with all their knowledge and gear could not. Now its gonna cost nearly a grand to fix something that I had planned to fix myself.Unfortunately I found out too late to stop the work Still love my wife tho Quote Share this post Link to post Share on other sites
