electical "pulse" is happening in all my lights. Inside and out. car still starts fine and have not had dead battery problems. has been getting steadily worse over the past 2 months......where do I start?

ground wires

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-justin

1987 300TD, 1987 300TD
2008 R32, 2000 Passat Wagon

Had this happen and it ended up being alternator brushes getting worn low on the 240D....Was still charging ok but apparently they were skipping on the rotor copper feed rings while under load causing the flicker....anyway that seemed to have been the cause....after I replaced the brushes, flicker went away....Previous post recommended ground wire cleaning and tightening...Always good advice and very important for all electric devices ....I even added an extra heavy ground wire from the Alt. frame to the battery....

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

I tend to agree with the alternator not providing constant output voltage to the battery. The only other thing that might be a remote possibility in my thoughts is the glow plug circuit flickering on and off. That is very unlikely but just disconnect your glow harness plug if you want to check that out with the car running. Again very highly unlikely, just a miniscule possibility. Takes no time to eliminate it as a possible cause though.

Do your lights brighten when you step on the throttle? If so the voltage regulator might be at fault. It's easy to pull out, so pull it and inspect the brushes. Each brush should be about 1/2" long. If they aren't you probably need a new one.

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NO....And the pulse is not effected by RPM's either..does not speed up or slow down with engine speed

This one is curious....Hope there is no Mother-Ship hovering nearby...Those pesky abductions can be trouble......
Could you describe the pulse..? Is it a rapid flicker or slower changing rate ? ...I guess what would be the number of times per second you could estimate and does it change frequency or level according to the electrical load...?
You could try pulling the fuses one at a time while it is running to see if you get to one that changes it.....

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

My 81 300CD did this only when started cold. Was a corroded battery clamp on the negative post of the battery and a loose alternator belt. removed clamp, cleaned and reinstalled. Tightened alternator belt. Please list your type and year of Mercedes in your signature. Was necc to look at your public profile to determine what type/year car you owned.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.

The rate is about 1 sec bright, 1 sec dim. I have noticed this same rate in the daytime, without lights on , happening by looking at the lighted radio face. It does this consistantly......even at the end of a 10 hr straight through drive. I will clean the battery contacts and see if that helps, but have not had any problems starting. Belt seems snug but not overly tight.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Try the fuse pulling like a previous post said and next I would change the regulator/brush pack just to eliminate it as a problem source since it does cut the rotor current off and on to regulate electrical input to the whole system....Easy to change ....2 screws on the rear plate of the Alt....unhook battery first...

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

ok, I removed fuses 1 at a time......no difference
I'll have to get brushes on tues. and try that.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

Might want to just pull the brush /Reg Assy....clean the contact areas and reinstall....My brother an E.R. Doctor from N.O.L.A. says..... taking something apart and putting it back together fixes it 90 percent of the time...and if you take it apart enough times ...eventually you will have enough parts left over to build two of them......

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1978 Yellow 300D (The Mustard Toad)
1980 Blue 240D (The Iron Toad)
1989 Grey Mitsu.4WD Mighty Max Pickup (Needs a Diesel transplant bad)

(Open the pod bay doors HAL)

I cleaned battery cables to no avail....still happening. I also ordered the brush/reg assembly and it will be in on Tues morning. for today I am going to remove the old one, check,clean, and re-install to see if that helps.

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81 Mercedes 300SD 289k.......SOLD
82 Mercedes 300CD 252k......slow ride

82 mercedes 300 SD...mi Unknown
83 Mercedes 300D ????ksniff..gone too
84 Mercedes 300D 148k........SOLD
85 Mercedes 300TD 386k and holding some one elses project

It sounds like your voltage regulator is going wonky! I had a simillar problem on my 300D and when I installed a new voltage regulator, it stopped!

To verify a properly tightened alternator belt, try to rotate the alt pulley by hand against its normal rotation. If it rotates at all, the belt is loose. And more than likely the belt is now glazed and wont grip well because its been loose.

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81 300CD (sold) 1972 280 SEL 4.5 (sold) 1966 250 S 4 spd (sold) 1974 450 SL (sold) 86 BMW 325ES (sold), 1973 280C (sold) 1988 300 SE.