Mercedes-Benz Forum banner

1 - 2 of 2 Posts

·
Registered
1984 Mercedes Benz 280SE 5-Speed
Joined
·
85 Posts
Discussion Starter #1
Hi,

Does anyone have the charging circuit wiring diagram for a 1984 M110 280SE?

We are having a mysterious no charge condition.

We replaced the alternator and it worked for about a week. Then I had a dead battery after an hour of driving. We suspected a leak to ground in the starter and replaced the starter.

We removed the NEG battery terminal and checked for continuity between the NEG cable and the NEG on the battery and found no continuity. It really seems like the battery is draining (only) while I am driving because the when enough time has past (about an hour of operation), I can expect to first hear a slight hum from the seatbelt warning light which will get louder and then leads to "battery is about out" symptoms. It is very predictable.

VERY WEIRD THING: If you start the car, then remove the POS and NEG battery terminals, the car continues to run until the key is turned off. I think this is the key symptom.

There was corrosion under the battery tray (previous owner had replaced tray and you can still see light corrosion under that) which may have possibly damaged the wires that enter the cabin under the battery. Maybe there is a short circuit in that vicinity?

I was hoping to look at a wiring diagram to help diagnose this. The car is a Euro model. I am mainly curious how the charging system connects to the fuse block, and how the fuse block distributes power (the one for the car and the black one (with the big wires ALT, BAT, etc. on the passenger side of the engine bay)). If no one has the diagram, words would be fine also. I really just want to isolate the leak.

In my searching, I came across a MB website where you give your credit card (but don't pay) for access to technical documentation. Is that something I should do? I can't remember why I passed last time, but it may have been a US site and I figured it might not even have Euro documentation. Would this access get me all the documentation I could ever want (ie even stuff like the manual gearbox overhaul)?

Thanks,
 

·
Registered
1966 200 Diesel; 1985 500 SEL (wrecked); 1991 420 SEL; 1979 280E (Home Market); 1993 190E 2.6
Joined
·
584 Posts
I had an Audi that did the same thing. (88 5000 CSQ) It would start with the warning lights coming on faintly and the headlights eventually dimming until the battery was completely flat. Shoddy rebuilt alternators ended up being the culprit. They would last about 10 days. I think we went through about 4 of them before getting a good one. Seems that some pretty poor quality voltage regulators and brush sets end up going into a lot of rebuilt alts. The voltage regulators and brush sets can be replaced rather easilly and inexpensively.

My girlfriend wrecked the car about 8 months later being an idiot and not paying attention, so I dumped her. I miss that particular car in the winter, but I am glad that particular girlfriend is gone. I ended up buying my first Benz after that crash/breakup so in the end it was a win/win for me.
 
1 - 2 of 2 Posts
Top