As part of getting the new car I do some cleaning and replacing the usuals. I was doing the belts/ idler pulleys and the front of the engine was caked in dirt. I disconnected the battery, unplugged the alternator and took that out to get below. All went well and I reinstalled.

Connected the battery back and nothing. I get some seizure-like flickering lights on the cluster, some interior lights/DRLs and relays(including the 30g)/hatch lock going wild in the trunk but nothing else; key even gets stuck in the ignition. Im getting between 3V(up to 6V with charge connected) between the battery terminals when its connected. Removing the battery and hooking up to the charger I easily get 12.4+ Volts almost immediately.

Are there any common faults/relays/fuses that I should check before my electrical hunt? I disconnected the IBS sensor and got I drive to pop up but still the same symptoms.

Car is an 07 530xi E61

 

Run an experiment and pull the battery from your other vehicle and place it in 530.

 

you ever get this figured out, kind of curious what might cause such a problem?

 

Still working on this; All fuses and relays good. Vehicle has 12.5V in the evening and in the morning it is dead ~3V.

Unplugged IBS: Same result, New battery(Old one was smaller than it should and I doubt registered): same result. I'm going to have to start pulling modules to see if the drain stops I guess

 

I would pull fuses not modules.

 

You mentioned, your going to have to start pulling modules to see if the battery drain stops.

While reading past parasitic drain issues, one of the problems that surfaces is the Blower Motor Resistor going bad.

When it goes bad, it will drain the battery.

 

Well I'll start with the fuses/relays (for modules) first. But since many are tied together I may have to unplug the harness for the modules later.

Blower motor eh? Thanks Ill try that one too.

I'm also getting a code for DSC (5D8D) DSC hydraulic Pump. the AWD/ABS/DSC/EBV light comes on every time I go over 10k. Code gives me no hints to what it means; never had that come up on the drive home either.

 

Ok, odd electronic issues are surfacing that are peculiar and may not be valid faults.

Many times when when the dashboard lights up like a Christmas tree or the engine is throwing codes at random its a confirmed voltage gremlin.

When this happened to my car, I had to replace the voltage regulator in the alternator.

I also tightened the battery jump terminal block under the hood.

 

Good call on the jump terminal. Mine had a little bit of corrosion so I tried that.

Also I just noticed some electrical humming coming from my waterpump. Still continues even after 20-30 mins (well after the car goes to sleep) I might have to do some digging there

 

Well it looks like the water pump was the culprit. Unplugged it overnight and finally the car had power in the morning (12.5V at battery) and it started.

Going to try unplugging the rest of the coolant sensors and plugging it back in just to rule those out before dropping 1K on waterpump/thermostat/hoses. Funny cause the PO just replaced the WP a year or 2 ago(looks newer too)