Car in question is the 83 300D. Today while driving, suddenly the battery light, the brake warning light, and the reserve fuel light came on for no reason, and would not go off. All other electrical seem to work ok.
Checked the battery voltage and it is 12.87 with the car shut off, and 12.5 when idling. Rev the motor and the battery voltage does not change. So…… I think I either ate the alternator or the voltage regulator. However, the voltage regulator was changed about 3 months ago with a brand new one. Also the alternator belt is tight and the alternator is not making any weird noises or smells.
Any ideas, as I am 75 miles from home and will be nursing it back before dark? HELP.

Glenn

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

If you Car will start; start it and drive it home.

If you are worried about the Turn Signals and Brake Lights Start the Car and Drive it some place and have them do a quick Battery re-charge.

You could buy another Battery and bring it along.

If the Engine will not start you need to get the Battery Recharged or someone who is willing to sit a while with the Jumper Cables on before you attempt to start.

If you Drive it Home Don't use an electric accessories.

You could buy another Voltage Regulator and hope that that works. Or see if any Wires borke or got disconnected or have bad connections.

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84 300D, 82 Volvo 244Gl Diesel

I think I would pull the voltage regulator and take a look. Even if thats the problem you probably cant fix it and dont have a spare so maybe get the battery charged up and drive home. I have never needed to do that but you shouldn't have a need for much battery in daylight once you get fired up. Where are you?

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1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

Your running voltage is low ... should be 13.8 to 14.6. Check your meter by checking voltage on any battery, clock, flashlight ect.

A good very very basic "how to check your alternator voltage" video. Many folks do better with pics than words.

A basic digital meter can be had from our favorite auction site for $5 to $10. Less if you are lucky and patient. Two or three are nice to have.

How to Test Alternator Voltage Output (AutoUpkeep.com) - YouTube

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1985 300D 198K sold
1982 300D 202K
1989 300E 125K
1992 940T

"If you dont have time to do it safely, you dont have time to do it"

"The democracy will cease to exist when you take away from those who are willing to work and give to those who would not."

Ok folks....I got her home. She started ok and I managed to get home with minimal use of any electrical accessories. Checked the voltage with a meter at the battery a few minutes ago. 12.21 volts. That is after over an hour of running time after starting it. Rev the motor and the battery voltage never changes.

Now to troubleshoot.

1.What would cause the battery light, the brake warning light and the reserve fuel light to come on and stay on all the time?

2. I know the battery warning light ties in with the charging circuit somehow, but how? Is there anyway if I pull the instrument cluster to jumper around the battery warning light to see if I can get the thing to start charging again?

3. If I take the instrument cluster out, does anyone have a list of what each pin on the big connector goes to or the signal/voltage it carries? I can start checking for shorts or bad grounds.

4. Lastly, since everything else works just fine (signals, tach, heater/blower, lights, radio, etc.....what would be common to the brake warning light, the battery warning light, and the reserve fuel light. If I can find that common point, I have a place to start.

Many thanks for any help/assistance

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

The Battery Charging/Warning light needs to have a good light Bulb in order excite the Alternator to start Chaging. In your case since the Light itself lights up your Bulb is OK.
The No Charging Warning Light connects to the Blue Wire on your Alternator Connector (the single small Slot) passes through the Ignition Switch to the Ignition Switch to the Alternator.

If you pull out the Connector and stick your + Meter Probe into the Small Slot and gound the other Probe you should get no Voltage with the Key off and slightly less than Battery Voltage with the Key On and the Engine not running.

On the 2 large Slots on the Alternator Connectory you should always have Battery Voltage.

If you remove the Alternator and take it for a free test that will tell you if it is Charging or not. If it is OK it is a good bet you have a Wiring issue with a small chance the Ignition Switch is shot.
The Alternator has to have a good Ground to function. Some have clipped one Jumper Cable onto the Negative Battery Terminal and somehow attached it to the Alternator Case. If it starts charging when you do that you have a bad Ground connection somewhere.

On gas Cars I have seen a similar thing happen to the Warning lights and even the Seat Belt Buzzer went one when the Alternator stopped charging and the Battery Voltage got low.

I actually drove like you did. The Alternator stopped charging, Warning lights on and the Seat Belt Buzzer on. I continued to Drive to where were were supposed to go a Lake; we left the Car running and got out an viewed the lake for 5 minutes or so and got back into the Car and drove off.
About 1/2 way back We pulled over and had the Battery Recharged while We got something to eat.
After that We drove to a Friends House that was closer and used His Battery Charger and eventually drove Home.

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84 300D, 82 Volvo 244Gl Diesel

I think you have a bad alternator.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

^^^^^^^^^^^^^^^^^^

Like minds.

^x3

It may well just be a matter of replacing the brushes in the alternator.

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Jim

Well, here is the latest. Still no charging voltage. I pulled the instrument cluster and made sure the large connector was in solid. It was, removed it and re-connected it....no change. Pullled the fuse box cover and just for the hell of it checked all the fuses with a meter. All are good. Pulled the voltage regulator out, and the posts are about 1.5 to 2 inches long and have a nice shiny concave edge. Put it back in, no change

So.....I am going to order a new voltage regulator and try it. Worst case scenario, I'll have a spare. Called the local Napa and they have a replacement alternator for $95, and they can bench test alternators as well.

I do have a few questions though, so please bear with me

If they test my alternator and it tests bad, how will I know it is actually the alternator and not the voltage regulator that is bad? Or would you suggest trying a new regulator first and if no change, then try the alternator?

If I have to get an alternator, I know I need at least 55Amp (65 would be better) but is there anything specific I need to look out for (any gotcha's that could bite me). I'm hoping it will come with a pulley, but if not, how hard is a pulley swap?

Lastly, is there a good how-to on pulling and replacing the alternator? It looks fairly straightforward, but I have never had to pull one on a OM617.

Thanks again for all the help. Right now I am chasing a no-start fuel pressure issue on my wife's car, the truck's turn signal multifunction switch fried and now the 300D is down. SHEESH!!!!

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

I think it's a bad alternator. You need an impact wrench to swap the pulley. Not a difficult job to replace. The lower bolt sometimes seizes in the bushing.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

You are correct; if the Voltage Regulator is no good the Alternator will test as being no good.

Were you able to test the Alternator Connector; the one at the Alternator?

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84 300D, 82 Volvo 244Gl Diesel

No, I was not. It started pouring down rain and I have another car in the garage right now, so I called it a night. I plan on checking it out tomorrow if the weather behaves.

Good to know my hunch was correct about the regulator and testing the alternator.

I think my best course of action is to test the connector wires. If they are ok, then get a new regulator and try it. If it still acts bad, then pull the alternator and get it tested/replaced

What do you think?

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)

Before you pull the alternator, check across the battery for AC voltage. You should not have very much if any. If you do have AC voltage, it could mean that the rectifiers in the alternator are shot - replacement is then indicated. A final test on the bench couldn't hurt for final verification.

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Codifex
1981 240D ChinaBlue (Got her running with a donor engine.)
1983 300DTurbo w/sunroof.
1984 300TD manual sunroof. (Electrical Gremlins)

I will do the connector check and the A/C voltage check today after I get home from work. Boss called me early and asked if I could work over, so it might be an 12 hour day so I may not get to it until tomorrow morning. I'll post if I find anything unusual.

__________________
2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)