Sitting on the side of 485 with a dead battery... - PeachParts Mercedes-Benz Forum

oilslick · #1 10-09-2015, 02:58 PM

1993 300D 2.5. Just put in a new battery. Drove to the Mercedes dealership in Northlake to pick up my new key. While driving home the abs light and the srs light came on. The AC compressor started cycling on and off. I pulled over just before exit 16 (Newton/Brookshire) to investigate. Shut the engine off but now it will not turn over. The new battery is dead. I had no alternator light come on. My oil, water, and alternator lights do not illuminate when the key is turned on but the abs, srs, asd, and glow plug lights do. Stumped.

leathermang · #2 10-09-2015, 03:12 PM

Too Late for you this time...
but for other people.....
one of the nicest backups of our Diesels... is that once running ....they are strictly mechanical... do not turn them off unless you really really have to until you get to a ' safe place' to deal with them....
People have driven across complete STATES without the electrical system working... when that involved overnight distances... .they left the car idling over night...or parked it on a hill to roll start it from.....

dude99 · #3 10-09-2015, 03:13 PM

All the connections nice and tight? I'm thinking the voltage regulator in your alternator went south and took out your OVP relay fuse. Then when the alternator stopped charging the battery drained resulting in your no start.

oilslick · #4 10-09-2015, 03:20 PM

Yeah, I know I can make it without the alternator and battery functioning but the battery is less than two hours old. I shouldn't have relied on that but I did.

The fuses in the ovp are still good. I believe it's the alternator that has died. As soon as someone comes to help jump start the engine then I guess I'll sit here and and wait. LOL!

Maxbumpo · #5 10-09-2015, 03:59 PM

Check the fuses CAREFULLY, I think you will find that either #5 or #7 has blown. I had nearly identical failure mode, the oil pressure gauge suddenly showed zero oil pressure. I immediately pulled off and shut off the engine, hoping to save it, and then it would not restart and only half the IP lights were coming on.

Maxbumpo · #6 10-09-2015, 04:06 PM

Rest of the story. I checked the fuses (in the dark, didn't have a good light) and didn't see the blown fuse. Waited for the tow truck, got towed to favorite Indy thinking that my motor was seized tight. Very dejected.

Got dumped at Indy's shop right at 8 a.m., Hans and his mechanics are drinking coffee and discussing the days work when I come in with my tale of woe. Hans listens and then says "Come on guys, I want to show you something." Out in the front of the shop he pops the hood on my car and opens up the fuse box, pulls out fuse #5 (or 7, I'm not sure which) and it is blown. Replace with a new fuse, car starts right up just fine and good oil pressure again. No charge, much relief on my part.

oilslick · #7 10-09-2015, 04:39 PM

All my gauges work. They never stopped working.

dude99 · #8 10-09-2015, 06:00 PM

Check and change the voltage reg\brush assembly before you bother to replace the alternator.

dude99 · #9 10-09-2015, 06:00 PM

Also, did you check the fuses with an multi meter?

oilslick · #10 10-09-2015, 06:35 PM

A friend came and we used his car to jump start mine. Drove home. Replaced the alternator with a spare one I had. All is well...for now.

Junkman · #11 10-09-2015, 08:19 PM

Keep the old alternator. If it has the voltage regulator mounted to the back of the alt, that may be your only problem. Buy brand name if you replace the voltage regulator. Bosch I think.

vwnate1 · #12 10-09-2015, 11:09 PM

Yes ~

VERY important to only use Bosch branded regulators ! .

They're only a couple Dollars more , last longer and best of all , have higher voltage @ idle speeds .

NAPA has the brushes so you can repair an old regulator you pulled out of a junk VW , Volvo , Saab or myriad other European cars....

I carry a spare as the brushes wear out and the battery goes dead but the ding-dang red light never comes on .