Electrical issue?

[Oif2vet]

Hey all, new user but been following threads for two+ years. Normally I have found answers to issues I am having or got GREAT ideas from doing research on these threads until now. Here is my issue today:

I have a 2003 525i with 83,000 miles. Recently what has been happening is occasionally while driving, my dash warning indicators will appear (traction control, battery, etc...) radio will flicker, the info "word line" ((time, date, mileage until empty, mpg info)) will "reset" and go blank, the car will briefly lose power then return back to normal. Sometimes it will do it a few times within a minute, others just once and then it won't happen for a few days.
When it's dark out and I am at idle in driveway I will turn on the overhead interior lights and map lights and I notice they will flicker. I step on the gas to move idle up for a few seconds and there is no change. Headlights seem to flicker a bit also. I tried to "duplicate" issue by pressing the power window regulator button to operate the window up and down. When the window was all the way up and still holding the button, it caused the dash lights to do it again and the car sputtered then reset. the headlights seemed to go a bit more dim while window was going up or down and when it was all the way up or down.
Car runs GREAT otherwise, no residual issues from it, seemilgly. What I have found from reading threads leads me to believe possibly a loose groung (where to look?), alternator, voltage regulator or loose neg. battery cable?

Any further ideas, insight or similar possibilities would be greatly appreciated. I look forward to hearing from all and finally getting online with everyone. Thanks a bunch in advance.

[Justin394]

That to me sounds like the voltage regulator in the alternator. The flickering lights would indicate a small amount of AC current making its way into the electrical system. When you load the system down the regulator may be failing and spiking more AC current into the electrical system and the OBC doesnt like AC. I would have the alternator tested. You can also check battery terminals as well as grounds. It doesnt hurt to check both.

~Justin

[Oif2vet]

Is the voltage regulator internal or external on the alternator? In other words is it possible to buy a voltage regulator seperate from the alternator or do you have to buy the alternator? I know with some other cars there was an external VR and could be adjusted up or down for output. I am guessing those days are long gone in the BMW world but wishfull thinking on my part if it was the VR.
What would be the most common areas to check the ground straps for poor connections. I live in AZ so the possibility of a corroded (rusty) connection somewhere is only a slim chance in my guesstimation. Battery compartment? Engine bay? Under dash, fuse panel area?
Common Voltage output from alternator should be about 14.5, sound right?

Thanks again.

[Justin394]

To be honest with you I havent had a chance to get deeply involved with these cars as of yet. From what I can see on my 540 the regulator is internal. Voltage should be 13.8-14.5 as for grounds again I dont really know much about where to look. The major place would obviously be the neg cable off the battery and the cables and terminals themselves. Im sure someone else with a bit more experience will chime in and hopefully lead you in the right direction.

[Oif2vet]

What is the easiest way to do a load test on the electrical system? Trying to see if I am getting too much amp draw on alternator. I can check the amp output but unsure if prob exists with the draw on VR. I always thought the flickering lights would indicate a bad VR.

[Justin394]

The only good way to do it is with a proper load cycling tester. I use to use a full snap-on unit it cycles load on and off while the car is running and gives you a report of what it found. Any good reputable repair shop should have one.

[Oif2vet]

Thanks for the info bro. I checked the terminals and connections last night after wark and they SEEMED tight enough but I rotated them a little just in case there was a little corrosion at the position they were in. Checked the ground strap and Neg. ground from neg terminal, seemed tight, no glaring problems. Guess we will see. I am sure I have to dig in deeper. I wonder in my scan-tool will read out any problems with anything even if no warnings on the dash display are showing...hmmmm. Any ideas with that? Should hold a code if something is amiss, right?

[Justin394]

It should hold a code if the fluctuation was enough to set one. You have to remember too that the OBC seems to shut down in your case so it may not be catching a code before it resets.