Flickering lights - where to start?

[TexaZ3]

I did a quick search to see if this has been covered recently, but can't seem to find anything on the subject, so apologize if this has been beaten to death.

I don't drive the car as often as I used to, especially not when I need to use the lights, so not sure when this all started, probably some time ago. But lately, I noticed that my lights all flicker a bit - dash, headlights, taillights, license lights, instruments - everything constantly dims and brightens, basically constantly changing in light output, almost like the current supplied to the light is fluctuating.

Which led me to think this is mechanical rather than electric, like failing alternator or generator? Or maybe relay of some sort? The car runs fins other than that. Battery charges fine. Does it when idling or revving, though it seems less noticeable when I'm on it. Any ideas where to start looking?

Thanks!

[BimmerBreaker]

I'd check the alternator and battery voltages first and go from there

[TexaZ3]

Battery is relatively new, how would you check alternator voltage? The gauge seems to be showing about 13.5v or so.

[SteveG66]

I would also check to make sure you have a good ground.

[TexaZ3]

I would also check to make sure you have a good ground.

Ground seems to be fine.

[deni2s]

Any aftermarket high power sound system installed without capacitor?

[gmushial]

If you're seeing steady system voltage, then I'd be looking for a loose connection - either on the + side, or a ground. But chase the voltage from the lights back toward the source... but if they are flickering you should be able to see changing reading on a voltmeter when you measure... or better an oscilloscope.

[TexaZ3]

Any aftermarket high power sound system installed without capacitor?

No, its stock. I had the car for over 10 years. Just now started flickering.

If you're seeing steady system voltage, then I'd be looking for a loose connection - either on the + side, or a ground. But chase the voltage from the lights back toward the source... but if they are flickering you should be able to see changing reading on a voltmeter when you measure... or better an oscilloscope.

I don't have the tools to do this. Might have to take it somewhere I guess.

[Vintage42]

Ground seems to be fine.

Why do you say that?

[rf900rkw]

Harbor Freight has a volt meter of sufficient capacity (for this) free with purchase. No excuse not to have one.

Item # 63604

coupon code 19225208

[gmushial]

No, its stock. I had the car for over 10 years. Just now started flickering.



I don't have the tools to do this. Might have to take it somewhere I guess.

mumble... I didn't read your post carefully enough... I was taking it to be headlights... but it sounds like dash lights... yes, I would look for a failing ground or ground connection.

[deni2s]

If it's only dash lights, then light switch probably needs to be replaced.

[kornfeld]

Harbor Freight has a volt meter of sufficient capacity (for this) free with purchase. No excuse not to have one.

Item # 63604

coupon code 19225208

I was about to post this exact thing. I have something like 5 or 6 of these multimeters. Makes it easy to keep one in the car, one in the toolbox, one at work, etc.

[PbFut]

Jumping in a little late. Flickering is generally a lose connection. Bad ground maybe, read lose connection. Alternator maybe, but you would normally see problems elsewhere as well.
On the subject of the HF MultiMeter. Every DYIer here should have at least 1. These things are so useful. In last weekend I used on Sprinkler system, FrankenCoupe, and the TrailBlazer. One in the house, one in the tool box, and one in the shop drawer.

[TexaZ3]

Ok, sorry for bringing back the old thread - just now getting back at tackling this. So the car has been flickering all this time, but this doesn't seem to affect anything, really (except for, well, flickering). So, I'm thinking it is ground after all.

Anybody can point me to the locations of the grounds to check? I have no clue what I'm looking for. Would be super helpful - thanks!

[Vintage42]

.

[rf900rkw]

How fast do the lights pulse? Is it steady? Does it follow engine speed?

[JustinHalverson]

There are diagrams in here, beginning at 0670.4 --
http://wedophones.com/Manuals/BMW/20...g%20Manual.pdf

"Give him a fish and he eats for a day. Teach him to fish an he eats for a lifetime." Maybe good philosophy, but this is a pretty challenging approach. I have to say that I'm familiar with wiring diagrams and have used this resource myself, but using it to find a likely candidate for a ground fault that would cause the problems described by OP is no simple task. In fact, in my quick look through the document, I can't find any information about WHERE the main battery ground connects using this diagram. That would be the first place I'd check. I'm no where near my car right now, so I can't look at the wires. My recommendation to TexaZ3 is to look at the big fat wire coming off the negative terminal of the battery trace it to where it connects to the body, and or engine. Make sure that point is clean and tight.

The document is more helpful in finding specific ground points. For example, the ground point for the headlights appears to be on the fender near the shock tower. Finding that required finding the connector number in the section on ground distribution, then going to the section on component locations and searching for the connection number.

[Vintage42]

"Give him a fish and he eats for a day. Teach him to fish an he eats for a lifetime." ... I can't find any information about WHERE the main battery ground connects using this diagram...

I can see it's too much information and does not help the problem. Took the link out.

[TexaZ3]

How fast do the lights pulse? Is it steady? Does it follow engine speed?

Its pretty random pulsing, really. I don't think that its related to the engine speed at all. Will try to do a video and upload later tonight.

- - - Updated - - -

"Give him a fish and he eats for a day. Teach him to fish an he eats for a lifetime." Maybe good philosophy, but this is a pretty challenging approach. I have to say that I'm familiar with wiring diagrams and have used this resource myself, but using it to find a likely candidate for a ground fault that would cause the problems described by OP is no simple task. In fact, in my quick look through the document, I can't find any information about WHERE the main battery ground connects using this diagram. That would be the first place I'd check. I'm no where near my car right now, so I can't look at the wires. My recommendation to TexaZ3 is to look at the big fat wire coming off the negative terminal of the battery trace it to where it connects to the body, and or engine. Make sure that point is clean and tight.

The document is more helpful in finding specific ground points. For example, the ground point for the headlights appears to be on the fender near the shock tower. Finding that required finding the connector number in the section on ground distribution, then going to the section on component locations and searching for the connection number.

Thanks, will try this as well.

[TexaZ3]

Ok, here is the video. Not the best job in the world but hey....
Kinda hard to see on the gauges, but I think dome light, and especially headlights give you an idea. Same flicker on everything.

https://www.youtube.com/watch?v=uz2OoI1UJOs

[rf900rkw]

Okay. As I see it the flicker is the lights spike brighter for a few milliseconds, not dimmer. This is not good because you are feeding the voltage spikes into all of the electronics. I'm going to say the alternator / voltage regulator would be my primary suspect. This is the type of thing you will not catch with a standard digital volt meter. You might be able to see it with an older analog meter, small flicks of the needle. What realy should be used is a graphing meter or better (lab scope) to see the milli-second spikes.

[TexaZ3]

Okay. As I see it the flicker is the lights spike brighter for a few milliseconds, not dimmer. This is not good because you are feeding the voltage spikes into all of the electronics. I'm going to say the alternator / voltage regulator would be my primary suspect. This is the type of thing you will not catch with a standard digital volt meter. You might be able to see it with an older analog meter, small flicks of the needle. What realy should be used is a graphing meter or better (lab scope) to see the milli-second spikes.

I think you might be right, couple of times as I drove the car, noticed that voltage on the gauge is higher than normal ~14 volts. So, you think this is alternator? Where is voltage regulator located or is it built-in with alternator?

[TexaZ3]

OK, voltage regulator ordered, will report once I get and replace it.

[TexaZ3]

So a quick update - it was voltage regulator after all.
Replaced old Valeo unit with Hella, and all is good. Brushes on the old one were almost gone, and commutator has a pretty good size grooves in it, but still lots of life left. Alternator bearings are in good shape and have no play. Thanks all!