2003 3.0 electrical meltdown

Nauticare94 · #1 09-12-2018, 04:45 PM

Okay folks. I've got a good one for you. I'm currently waiting on a tow truck. While driving the AC stop blowing cold air. That was the only symptom I noticed. Stopped at a red light thinking maybe a shut off restart may help. When I shut off the BMW the engine stopped turning, but all the electrical stuff stayed on. The stereo and HVAC we're still on, as well as all the normal dash lights, however some things aren't correct. For instance, the car says I'm in Drive on the dashboard right now. It's parked and the key is removed. Brake lights are stuck on. Hazard's are working, however they're steady solid on the dashboard. Blinking all around the car otherwise.

Sponsored Links

srmmmm · #2 09-12-2018, 04:52 PM

Battery has retired.

2002 X5 3.0 348,200 miles - currently on it's third battery
2014 428i 40,000 miles

2004 325i sold at 123,600 miles
2001 325i sold at 66,000 miles

1970 Firebird Under restoration

Nauticare94 · #3 09-12-2018, 05:09 PM

Thank you for the quick response! Does it need to be reset when I installed a new battery?

srmmmm · #4 09-12-2018, 05:11 PM

If you connect a charger before you remove the old battery, you shouldn't need to reset anything (remember to protect the positive cable end at all times since it will remain "hot" with the charger connected).

Removing the battery without supplemental power to the car usually means you're resetting the key memory positions and radio settings.

Nauticare94 · #5 09-12-2018, 05:17 PM

Copy all. Thanks!

andrewwynn · #6 09-12-2018, 05:22 PM

I dont know what year started the need for battery registration. But a bunch of things will likely already have errors from the low voltage so I would get then all reset. If you don't have a second level scanner I would get one

Sent from my iPhone using Tapatalk Pro

Nauticare94 · #7 09-12-2018, 09:11 PM

Got it home and threw the charger on it at 2 amps. Swapped the battery out. Good as new! That was nuts...

andrewwynn · #8 09-12-2018, 09:15 PM

Scan/clear codes. You'll be surprised how many things trip from a low battery

Sent from my iPhone using Tapatalk Pro

oldskewel · #9 09-12-2018, 10:15 PM

Nauticare94 - glad you got it fixed. Is your alternator working fine?

Others - what was the key clue in the symptoms to point to the battery? I had no idea on this one. Is the AC shutting off a power saving clue (I guess these cars are pretty smart)? And then all that other weirdness???

andrewwynn · #10 09-12-2018, 10:21 PM

Definitely make sure you're alternator is outputting proper voltage so you don't ruin a brand new battery.

Usually a drained battery that starts Cascade failure is from alternator but you will definitely get a battery light on the dash by the time the AC and other things shut off.

Similarly to how in mammals the blood circulation gets cut off to the extremities to keep the core warm, BMW cars will cut off power to high drain things if the battery voltage gets too low to keep the engine running.

It's very important any time the battery is just replaced to confirm the alternator is outputting proper voltage. Use hidden menu to pull up realtime voltage and make sure the voltage stays between 13.5 and 14.5. If it ever dips even for moments below 13v that's a problem.

Sponsored Links