2003 bmw 325i lost power to windows,radio, windshiedwipers,instrument cluster lighting. no obd codes

that's because you didn't lose power so much as Grounding...for completion of the circuits...recommend that you take a coarse wirebrush and disassemble the bolt holding the battery 1/0 cable onto the chassis....wirebrush the chassis....with a pliers in one hand (so as not to damage the lug) wirebrush the lug too....put them together for restored ground potential....electronics are happy when they get good ground...I'm just sayin'~

cleaned grounds , items still not working

Check the voltages with a multi-meter...suspect the battery is not 12.5 volts but 10...the battery is defective~ check at the relay box and at the headlights (when on) today's tin/antimony alloy batteries refuse to accept a charge ten percent per year so in five years they really must be replaced...will NOT be able to have full output at that point~

Did you ever figure out what this problem was? I have the identical problem except the radio is working but it is not factory and could have sourced power elsewhere.. All fuses associated with these devices are good. I thought grounding but everything else in the car is working fine. Thanks Doug