Ronnie355

Haven't started my car in a couple of weeks so I thought I would start it today. After starting the car, I noticed the dome light was going from bright to dim and back to bright and so on. Idling pretty roughly too, just passed 58,000 miles.

Tonypw

iTrader: (1)

My 05 E55 is doing the same.

shardul

iTrader: (1)

drive it a bit and see if the issue is resolved

Ronnie355

What is your mileage? I'll drive it this weekend when the snow is gone.

.trunzx

Had this issue for a long time. Replaced battery and alternator and its been fine since.

harjothundal

Mine just recently started doing this... I've been diagnosing it myself for the past 2 weeks and am pretty certain it's either a bad alternator or voltage regulator...

Ronnie355

The alternator was my first thought too but the idling problem worries me a bit

harjothundal

the reason the idle is rough is because your car is trying to increase to rpm's to get the alternator to produce more current... i'm certain we have the exact same problem... i noticed this almost a year ago, but it was intermittent and only affected my exterior driving lights... recently it started affecting my interior lights and occasionally my electrical consumers will shut off while driving...

have you tried to monitor your voltage on the IC?

Ronnie355

No, today was the first time that I've started it in a few weeks. What did it cost to get an alternator?

harjothundal

I have not replaced the unit yet, I have a spare vehicle that I am driving for the time being until I get the time to focus on getting the alternator replaced. I have seen them range frmo 300-600 when doing a google search. You may want to test the voltage at both batteries after letting the vehicle sit overnight. My batteries test good, only thing left is the alternator or BCM...

Ronnie355

Thanks for your help. I'll test the batteries in the morning and then figure it out after that.

skratch77

Before you get a new alternator I would drive the car for a bit.You said the car sat for a few weeks right?this cold weather will put a hurting on your bat and if you are not driving it you should put a tricle charger on it.

Your bat is probably low and needs to be driven for a few miles to charge up.

Ronnie355

Yeah haven't driven it for awhile, just been sitting in the garage. I'm gonna check the batteries then drive it for a few days and see what happens. Thanks for the help!