Hello, I recently started experiencing battery drain in my Bavaria. It's not the battery, that's been tested. If left connected the battery is DEAD in 3-4 days. When disconnecting the battery cables I notice them slightly sparking as though they are using current even though everything appears off. I searched the car over as much as I can and the only thing I see is that there are two red smaller wires connected to the POS post. When I disconnect these wires the battery does not drain. I traced these wires to go the the "Load shedding" relay. This relay is thought to be located on the top right of the fuse box.(According to my Prospero garage laminated wiring diagram) I did the usual disconnecting of all fuses, made sure the power antenna is not stuck on, and am at a loss. Furthurmore, calling around in my area trying to find a shop, they all seem to NOT want to touch the car. HELP. I'm located in Ontario CA. Thank you, Scott
Do you have a digital multimeter with a 10A range? If so, I can talk you through testing it. Also, does it have an aftermarket radio (probably by now.) Number one cause of key off drains on BMWs that I have found have been aftermarket accessories.
Thanks for the help! I do have a multi tester with that range. I disconnected the radio and I still have the issue. That would be great if you could walk me through the process, any pointers would be great! Thanks, Scott
OK. You would set the multimeter to the highest amperage range and insert the probe into the correct hole on the front of the multimeter (usually they use a separate 10 or 20A fused circuit.) Set it to the amp range and then disconnect your battery cable negative. Make sure the key is off and any doors or glove box, etc. is closed but leave the front windows down (more on that in a sec.) Now connect the ammeter in line with the battery and cable. It doesn't really matter which order you hook it up battery to red, cable to black or battery to black cable to red so that any current flowing from the battery goes through the meter. One way will read positive amps, one will read negative. This should tell you how many amps the car draws with the key off. It should be much less than 1 amp (more like 20mA or so.) If it is less than one amp you may not be able to quantify it with the meter set up this way. If this is the case, remove the leads from the battery and place the red lead into the correct hole on the meter to read mA (most are set up this way, but if you post a picture of yours I can tall you more.) Then set the dial to the next highest range and hook it back up to the car the way it was before. This should show how may mA the car is drawing again. You can then get to pulling fuses to see which kills the drain. Anything in the 400-800mA range kinda screams light bulb. Check the glove box and trunk- if you open them and the drain does not change, there is the problem. If the drain goes up that is not your problem. Anyhow, if the drain is tied to the unloader relay, it is likely interior illumination, radio circuit, lighter circuit, AC or blower as these (and possibly more) systems are powered down when you start the car (the purpose of the unloader relay.) Need clarification? Please quote any bits you don't understand. Make sure you don't short or overload the meter or else you will have to go looking for a fuse for it at radio shack.
Thank you! I will be trying to follow your instructions and see where this goes. I appreciate your help, and will be posting the results. Scott
