E39 Problems part 2

So a few weeks ago I found out what it feels like when your brake booster fills up with water due to a poorly designed water drainage system, well last morning I went out to my car in the morning after a particularly rainy few days (that part becomes important later), got in turned the key, and all the accessories powered on as they normally would. I tried to start the car and, nothing. I hear a series of clicks and then all the lights came back on really dim. My first assumption was dead battery, I’d just bought a BT OBDII reader and left it in overnight so I figured it had stayed on and drained the system. To avoid a wall of text I’ll summarize what I tried in list form.

Jump start, no start/no crank

Charging Battery, no start/no crank

Battery connections, all good

Fuses, none blown

Key immobilizer issue, tried two keys

Replacement battery (free under battery warranty), no start/no crank

My breakthrough came when I was drying up some mysterious condensation that had formed around my battery box in the trunk. I was reaching around the bottom of the tray with a towel when my hand fell upon some deep standing water. I took out my trunk mat and found about 4-5” of water in the spare tire well. It was high enough to fully submerge these two boxes (you can see where the water line was)

Illustration for article titled E39 Problems part 2

I later found out that these are voltage regulators for a Hella Celis taillight retrofit (which I wasn’t aware I had :P ). I drained the water, disconnected the voltage regulators and the car started right up, albeit without tail lights. Tried to air dry overnight but ended up with the same no start issue in the morning after reconnecting everything. Next, figuring they were probably dead anyway, I put the regulators in the oven for a few hours (low heat!) just to make sure any remaining water was removed. Hooked them back up and now everything appears to be working normally again. Today I got some more major rain and I was able to determine that the water is getting in through the passenger side taillight gasket. I’ll be sure to throw some gasket maker on that over the weekend which should put the issue to bed. I’m actually staggered that these regulators were able to dissipate that kind of power without popping a fuse or causing a fire.


Also, looks at all these connections that were probably getting splashed every single time I made a hard left turn...

Illustration for article titled E39 Problems part 2

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