Strange Battery Drain?

[Copper9562]

Recently I've noticed that if I let my 91 BMW 750il sit for the week, its battery seems to drain just enough to where it won't start without a jump, but will start fine the next day or day after.
I did a little digging, like the "leaving it dark and quiet" trick and all I saw was a faint glow of the light that is under the switches for the windows. It was only in the center console though. Why is that, and what can I do about it? It seems a little strange that it's the only light that's on, but makes sense that it's the only thing draining power over the period it is.

Please let me know what I can do, as it controls the windows of course, and I would like to be able to use the switches I just recently cleaned and restored. For now, I've unplugged it to stop the drain.

Thanks!

Copper


Current Vehicles: 1991 BMW 750il Volvo 940 T-Wagon Turbo Ducati 1299(1486)

[shogun]

I would like to be able to use the switches I just recently cleaned and restored.

did you disassemble the switches when you cleaned them?
Did you notice that constant dimming also before you cleaned them?
Check the wires of the wire loom going to the switches, any blank wires touching each other?

In case the window switches are always on, and you checked all other items, the problem could also be the GM = general module under driver side rear seat. Another item could be the ignition switch. In case you have a spare GM, swop that in. For a test you could disconnect the ignition switch cable, remove the cover under the steering column and follow the cable.

Did you wait long enough, because the light switches off after 16 minutes the ZKE goes into sleep mode, when you do not lock the doors. https://www.bimmerforums.com/forum/s...IGN-switch-off

In general, closed circuit current consistently over 50 mA must be investigated. Depending on the vehicle's equipment, closed-circuit current by vehicle model is approximately as follows:

E31 50 milliamps
E32 50 milliamps
E34 40 milliamps
E36 30 milliamps
E38 50 milliamps
E39 40 milliamps
E46 40 milliamps
E53 40 milliamps
Z3 30 milliamps
Z8 50 milliamps
Here’s the whole pdf: http://www.princeton.edu/~sdepasqu/b...easurement.pdf

1. Check battery voltage is a minimum of 12 volts. If necessary, recharge the battery.
2. Switch off all other electrical consumers, paying particular attention to the telephone and any retrofitted special equipment.
3. If the battery is installed in the trunk, open the trunk and turn the lock to the locked position using a screwdriver or similar (simulates the trunk lid being closed). The hood must be closed.
If the battery is installed in the engine compartment, open the hood and pull the front lid contact switch fully up and lock in this position (workshop position, simulates the front lid being closed). The trunk must be closed.
4. With the exception of the trunk / hood above, all other doors / lids must be closed.
5. In order to simulate normal closed circuit conditions:
-- Open the driver's door and close it again (simulates somebody getting in).
-- Switch the ignition "on" for at least 5 seconds and then switch it "off" again (simulates driving).
-- Open and close the driver's door again (simulates somebody getting out).
-- Lock the car, arming DWA if this is installed.
6. Wait 16 minutes for consumer cut-off. (On automatic transmission vehicles, consumer cut off is visually indicated when the amber shifter LED goes out). Closed circuit current can now be measured.
7. Using the closed-circuit current measurement adapter 61 2 300:
-- Connect the red clamp (marked "BATT +") (1) to the battery positive terminal.
-- Connect the black clamp (marked "CHASSIS") (2) to a the ground support point on the body (or other suitable ground).
-- The green LED (3) illuminates to indicate correct installation.
8.
-- Connect the black clamp (marked "BATT -") (1) to the negative battery terminal.
-- The green LED (2) goes out.
-- Note: Any electrical overloading will be indicated by the red LED illuminating. In such cases, the adapter connection should be checked and corrected as necessary
10.
-- Set the multimeter to the10 amps measuring range.
-- Connect the multimeter to the adapter.
-- Disconnect the battery ground (1) from the body.
-- Measure the closed-circuit current on the multimeter.
-- After measuring the closed-circuit current, reconnect the battery ground cable (1) before removing the clamps. Then switch the ignition "on" for at least 5 seconds and then "off" again to prevent faults due to non-initialized control units.
11. Interpretation of Measurements taken with a Multimeter
BMW recommends the use of Fluke Models 83 and 88. Most multimeters have a "powersave" feature which shuts down the meter after a certain period of time. With the Fluke Models 83 and 88, this "powersave" feature is automatically disabled when using
"MIN MAX" or "AVG". Operating characteristics of other makes and models may vary -consult the operating instructions for details.
With the Fluke meter set in regular mode, and if systems are functioning normally, the closed circuit current will be seen to maintain a reasonably constant level, with momentary excursions to higher currents as system modules perform occasional update duties. These occasional fluctuations should be ignored. With the Fluke meter set on "MIN MAX", these occasional fluctuations (sometimes over 100 mA), will be recorded. As a result, care should be taken when interpreting the results when the meter is used with this setting. In general, the use of "MIN MAX" is not recommended for this reason. With the Fluke meter set on "AVG" (Average), the momentary fluctuations are averaged out.
This is the recommended setting to use...
If the average closed circuit current measured after an overnight test is within the value for the vehicle model (step 6), the system is performing satisfactorily.
If the average closed circuit current measured after an overnight test results in a higher than expected current, further investigation is required. In such cases, the use of the MoDiC is recommended (see step 12)

[Copper9562]

When I cleaned the switches, I completely disassembled them as they were sticky (from the car unfortunately being left outside for some time with the windows open). I didn't notice anything strange about the internal circuit that would leave me to believe it's the switches. I also noticed when I pulled the switches out that as soon as I disconnected the white connector(the one closest to the dashboard) that the lighting immediately went out. The rear passenger door switches were not glowing at all during this period, but do glow when the car ignition is on, and the lights are turned on, as it should. the light on the switches don't seem to go out after any period, but I'll be sure to check again.

The only battery that is installed in my model is the one under the rear seat that's a total pain in the ass to get to, but I still have the terminals I can use under the hood.
I'm not quite sure that this battery is the correct one for the car. It's a rather small yellow optima that the "not so bright" previous owner gave me when I bought it. It'll start the car, but I can't leave the car radio on for any extended period of time over 10-15 minutes, which one of my family members X5 can go for nearly an hour without having to worry about that.

Does this switch go to anything in particular besides the windows that I can check? One of the computers under the hood on the passenger side or something? I know that sometimes one of these computers can have a small problem with light timing and the hedgehogs that can leave the fan running for no reason.


Hope some of this extra info helps, If it helps any extra, I can drop my vin here so you can look up my model and specs.

[shogun]

Here are the wiring diagrams for all built years, there you can check http://shark.armchair.mb.ca/~dave/BMW/e32/
The ZKE = central chassis electronics controls this, that is the GM = general module under rear seat left side (in driving direction). http://bmwe32.masscom.net/johan/elec.../rearseat.html