The car has had charging problems for a while, now the headlights will cut out if the turn signal is used. The Interstate batt is new and voltage reg is new. The reputable shop nearby tested the charging system and found no faults. However, when I tested the charging voltage with my rinky dink voltmeter, I found the voltage to be pretty low when using all consumers. I don't remember the exact voltage but my brother was having trouble with the headlights when using the wipers, heater and stereo.

He also reports the stereo cutting in and out. Several times he's needed a jump after the hour long drive to work with the car not restarting 10 hours later. I took a look at it and when the key was turned to position 2, there was a loud whiney groan from the preglow time relay. I removed it and noted some wierd looking stuff to me on the wiring board, but electronics are really beyond my scope. I can email a picture to someone, but posting pics remains mysterious to me. (Can't get the pics small enough)

With my untrusty Haynes manual, I see that the turn signal indicators in the cluster are connected through the preglow relay. Now I wonder if this discovery is too easy, that maybe this is a symptom of another problem because why would the preglow relay cause the battery to not charge UNLESS! the glowplugs were operating longer than they should be.

Now I will do a search and see what I find.

Thank you kindly.

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

The SD would do similar things for awhile. After about three months of this BS, I finally took the alternator in and had it rebuilt. At that time, it finally refused to charge, at all, so the problem was obvious.

I understand that the brushes start to become intermittent before they finally wear out completely.

So that is not related to the regulater?
The brushes are not replaced on the back of the alt, but requires a removal and rebuild?

Thanks B.C.

Did you pull the head on the SDL?

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

E-mail me the pictures at asemastermechanic@gmail.com

Three points:
Voltage regulators are cheap, suggest you replace it.
The wires from alternator go to a terminal block on right inner fender well; remove all wires and clean them.
Remove ground cable from body to engine, and clean both ends + mounting points.
WARNING:
Do not mix up the wires while cleaning....

__________________
ASE Master Mechanic
asemastermechanic@juno.com

Prototype R&D/testing:
Thermal & Aerodynamic System Engineering (TASE) Senior vehicle instrumentation technician.
Noise Vibration and Harshness (NVH).
Dynamometer.
Heat exchanger durability.
HV-A/C Climate Control.
Vehicle build.
Fleet Durability
Technical Quality Auditor.
Automotive Technical Writer

1985 300SD
1983 300D
1984 190D
2003 Volvo V70
2002 Honda Civic

https://www.boldegoist.com/

I never did replace just the regulator, or the brushes. But, I understand that this can be done at relatively low expense.

The head is currently off the SD.

Check your grounds.......... Batt.-Chassis and especially Chassis-Engine.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

I'm thinking maybe the preglow relay is okay. I will send you the pictures whunter in a day or two. I used a booster battery and there was no bizarre whining from the relay and the car started fine.
Charging voltage is 13 max according to my cheapo meter.

I will try cleaning those alt connections on the right side. Regulator was replaced. There are so many multiple problems, you'd think it was a ground connection or the alt.

Thanks for the help

Brian, I thought you had an SDL. Maybe that's why are messages where a little confused

__________________
63 220S W111
76 300D W115
2013 VW JSW TDI M6

previously-
73 280 SEL 4.5
86 300E 5 speed
2010 VW Jetta TDI M6

I do. See the sig.

But, you asked about the head. I've had to pull the head on the SD due to a bad head gasket. It has turned into a serious "while you are in there" project.