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93 318is Charging and Battery Issue

2K views 7 replies 6 participants last post by  ZeGerman 
#1 ·
Hey guys, new to the forum and also new to BMW. I just recently bought a 93 318is with a 92 325i m50 engine. Runs and drives great but it keeps dying if i let it sit too long (like over night or even an 8 hour work shift). I have a brand new battery and the alternator test good. I took the positive terminal off the batter when running and it didnt die whuch tells me that thebalternator is actually good. So something is drawing the battery dead. A weird thing is that when I shut it off and open the door I am still able to roll the windows up and down and use the sunroof(no radio in it right now that can draw anything). Is this supposed to be this way? I always thought that when you open the door it tells the ecu that "nobody is in the car" and shuts everything off, or that is how all my other vehicles have been at least. What could this be? Shorted wire somewhere? Something that keeps drawing juice when it isnt supposed to be? I cant figure it out and it sucks not having a vehicle. If you guys could please help me out that would be awsome. Thanks for reading.
 
#2 ·
Welcome to Bimmerfest!

Remove the negative battery terminal. Put a DDM set to amps connected between the post and cable clamp. Since you'll have the trunk open, remove the bulb in the trunk so it's not putting any drain on the battery. Leave the doors closed. If there is a parasitic drain, you'll see something more than 40 milliamps draw. Start pulling fuses one at a time and have someone watch the meter. If removing a fuse makes no difference in the reading, put that fuse back in. When the reading drops, note which fuse it is, and look up what circuit that fuse controls. Leave that fuse out for now. Go through all the fuses, leaving out those that show a drop in the reading when removed, and note which numbers they are (the fuse numbers are on the plastic cover). Eventually you'll show 0 amps drain. That'll mean everything is disconnected. The clock will draw about 40 milliamps. Anything much over that will be your parasitic draw. The fuse circuit 'map' can be found in the Bentley manual. You can download one here: http://www.mikerophonerecords.com/bimmer/e36bentley.pdf
 
#4 ·
+1 to what ken stated, and to answer the question about the windows, no, they should not open/close when the door is open and the key is in the off position. all accessories will operate with the key turned to the off position until one of the doors is opened, then the system will turn itself off.

i have played with this feature for many minutes, so i believe it will remain "on" until a door is registered as open.


oh yeah,...and welcome to the fest!!:thumbup:




df
 
#5 ·
Maybe that is what is draining the battery. I turn the key to off, remove the key, open driver door and windows still roll up and down. I get out, leave door open and open passenger door and still the windows roll up and down. So what could be making the system not to shut down? Even after I disconect the battery and reconnect they still roll up and down with the key in my pocket.
 
#6 ·
What ever is allowing the windows etc. to still work is most likely the source of the power draw. To make things a bit easier to check the circuits you can disconnect the positive post in the engine compartment - the one you would jump start with - and put your meter there instead of using a battery post connection in the trunk. Then you can watch the meter as you pull the fuses - one man job.
 
#7 ·
318i Current Drain / Charging and Battery Problems

Good comments as one needs to know if there is a current drain. I was riled by a similar problem with my daughter's '94 318i as it appeared to have a current drain, but it was inconsistent. The battery would go dead after a week and the car kept blowing one of the fuses. We found the problem when she had just closed the trunk lid just after I had replaced a fuse, causing it to blow again.... Eureka.... the location of the problem could now be isolated.
After stripping the casing off the wiring loom going to the trunk lid where the wiring flexes, one wire was found completely severed and many more were bare and obviously cross feeding power causing strange things to happen. Obviously BMW blew it on this wiring design as the loom is flexed excessively each time the trunk lid is opened and closed. Repairs were made to each individual wire and then wrapping the entire ass'y in electrical tape. No more problem, but I'd like to replace this part of the cable ass'y to avoid a repeat.
Hope this helps. It's the first time I ever ran into this problem on any vehicle, but then this one is 20 years old! :)
 
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