Serious battery draw 1990 BMW735i

[sask735i]

I have a 1990 BMW735i that has a serious battery draw. If the car is not used for 3 or 4 days the battery will be completely dead. I had this car imported to Canada from Japan in Feb 2007. It had 34,500km on it and it now has 42,000km. When I first got the car it had this problem . Thinking the battery wasn't holding a charge I installed a new one. It did not help. The other day I put an ohm meter on the battery and with everything shut off it is drawing .16 amp. I pulled all the fuses and relays with not change to the amount of draw on the battery. When I pulled the LKM it dropped to .08 amps and when I pulled the CCM it dropped to .01 amps. Is it possible that the CCM is the problem? If anyone knows of any other thing it could be I would surely appreciate hearing from you . Thank you very much for your time.

[lincolnmaster80]

Nice to see a fellow Japanese spec car! I too have a Jap spec car that was imported to Canada in or about Jan of 2006. Mine is a 1990 750iL though.

Anyways, on with your battery problems...

Well, hooking up an ammeter is a good start. Pulling the LKM and CCM is another good idea. Though I would leave those in for this test and start pulling fuses and replacing them, one by one, and see exactly which system the drain is on. This will help you isolate what might be causing it. I have a feeling that the fuses you pull will be related to the LKM, as the culprit is usually something to do with the lights most of the time.

If that doesn't find it, try disconnecting the alternator...the alternator has been known to cause problems too...

[sask735i]

Thanks lincolnmaster80. I really do appreciate the reply. I did try pulling one fuse at a time along with the relays one at a time, and there was no change. I will try unplugging the alternator and see what happens there. I wished there was a place here to get used bmw parts so I could try another CCM or LKM to see if that is the problem.........Thanks for the pictures of you car........pretty sharp. I really like mine and its amazing the conditions this vehicles are in . The only thing is that I wish I wouldn't have started reading different threads on these cars. There seems to be so much that can go wrong with the. I honestly didn't expect this from an expensive car such as this. Ohhhhhhhhh well. Mine also came with aftermarket wheels 16". When I picked it up in Burnaby I purchased a set of stock wheels for it also. Thanks again.......any more info would be greatly appreciated.

[lincolnmaster80]

RE: Didn't realize so many things can go wrong with them.

Well, keep in mind these are Japanese vehicles. They have an inspection system over there that basically is bumper to bumper. Anything that is integral to the safe operation of the car is inspected.

Some of the things you will want to keep watch on are basically the service items. Seeing as you have the bix-six motor, parts are a bit cheaper. For instance, a set of OEM spark plugs for me car cost me about $700...at that was as cheap as I found them without buying of eBay, where who knows where that stuff comes from...better be safe than sorry I though. Your car I've seen prices as "cheap" as $100 for the set, seeing you only need 6 wires and you don't need the spark sensor like the V12 has so that it can syncronize the firing and injection...

Other things you will keep an eye on eventually, at about 80K-100K are the subframe mounts (aka Beer Cans), rear trailing arms (aka Dog Bones), front top strut mounts (which will contribute to violent shimmy), upper control arm bushings (which will also contribute to violent shimmy), brake caliper stick (which can cause violent shimmy), rough idle issues (ignition coil, distributor cap, distriubutor rotor, spark plug leads, spark plugs, fuel pump, fuel pressure regulator, fuel filters, air filters, MAF sensor are the biggest contenders). But remember, most of the so called "problems" are service items. They would have had to been replaced whether or not you owned the car since new. And if the last guy didn't do it, well, these things need to be replaced. And if they last another 100,000KM's, it's well worth the $50-$1000 parts bill...cuz you won't have to spend that money again for another 100,000KM's. In the last year, I only put about 10,000KM's on my car...so for me, the parts I replaced so far are good for an estimated 10 years.

And of course, the die hard 7er owners (I'm am one and am not one) say that is DIY'ing should be a pre-requisite to ownership of these cars.

All in all, these are amazing cars! Keep on top of their maintenance and look after stuff as it arises, and you'll see 300,000km's outta her no problem!

As for your LKM and/or CCM being the problem, it's possible you have already found the problem...

http://www.autopartsonlinecanada.com - cheap parts, orders over $75 is free shipping
http://www.bavauto.com - not cheap but not expensive as the dealership, but they have a lot of parts...
http://www.autohausaz.com - cheap parts too...

Hope this helps...anything else you need, post it up! Or if you need some more info on what to look for on any of the above bushings, etc mentioned above, let me know and I'll try to help in anyway I can...

[webmasterz]

When checking for a drain it is important to let the electronics stabilise for 10-15 mins first. Then start pulling them one at a time, mine was down to the memory seats/mirrors and seat motors. Cant remember what number but it was one from under the rear seat. When pulling the fuses from under the bonnet/hood the alarm and bonnet light will be active!
Secondhand parts are cheap and plentiful in the Uk and shipping isnt that expensive to canada I'm breaking an E32 735 at the moment

[lilant612]

I have a 1990 750il with a serious battery draw, and I've read around, I've heard that the cord that leaves the alternator trails next to the engine and can become corroded around 140k. I'm sorry but I missed your mileage, I'd say that should be the last thing you'd want to look at, though. It appears my 750 would need some serious work to get to that cord, as the alternator is midway down the front drivers side of that huge block.

[sask735i]

Thanks for the info webmasterz. I unhooked the alternator and it made no difference. The battery was stone cold dead tonight (Tuesday Aug 28) I am going to pull the CCM and let the car sit for a few days to see if the battery goes dead with that removed. Hopefully I can find the problem.....Thanks again

[sask735i]

Well.....unfortunately I am still having trouble with the draw on my battery. I pulled the CCM and let the car sit for 4 days. On the 4th day it would not start. To date I have pulled all the fuses and relays (one at a time) and tested for draw , unhooked the alternator and now pulled the CCM. I guess the next thing I will try is pulling the LKM for a few days and see what that does. I do not know where to go from here. Any help would be greatly appreciated. I would really like to thank all who have replied.

[Bear]

have you tried using a volt meter or test light and pulling fuses one at atime and plugging in the meter or test light in the fuse recepticle? You should have no voltage or no light if the fuse port is not shorted.

[sask735i]

Thanks Bear, I will give that a try

[sask735i]

Just wanted to let everyone know that I finally fixed the battery draw problem. I replaced the CCM and everything is great. Thanks to everyone for their input

[Silverado514]

Where can I found this CCM in 1999 740i?

I had the same problem....

[lincolnmaster80]

Originally Posted by Silverado514

Where can I found this CCM in 1999 740i?

I had the same problem....

What's the last seven digits of your VIN number?

I can't say for sure, but I didn't think the later E38's had a CCM...something similar, but I might be thinking of another system perhaps?

[Silverado514]

Originally Posted by lincolnmaster80

What's the last seven digits of your VIN number?

I can't say for sure, but I didn't think the later E38's had a CCM...something similar, but I might be thinking of another system perhaps?

DF85074

[lincolnmaster80]

Originally Posted by Silverado514

DF85074

Appears I was thinking about another system.

The part number for the Check Control Module is '61 35 6 961 141'. You can try to phone BMW and get a price but I can garantee you it's gonna be about 4x the price.

Where can you find them? Ebay...

It would seem that the E38 CCM also has the LKM as one unit. So if you need to replace one, you might be looking at replacing both. In doing a bit of research, it seems you have to get it recoded. I'm assuming that means for your specific car, which is possible that only BMW can do that. I'll look a little further into this and see what I can find.

If not, you can check out the Roadfly E38 board. There's tons of guys and gals over there that probably know more about your E38 than I do.