OVP- overvoltage protection relay in 124 bodies is usually situated near control unit behind the battery. If i understood right, your cars code is wdb126125. One plase for the OVP relay in 126 is to the right (reffering to the direction of travel) of the master brake cylinder. There is another place for it also, somewhere on the wall of the engine compartament. This relay always has one or 2 fuses on top of it.
I have not worked on these cars because in Europe they are quite rare, but i had a similar problem on 124. This was a gasoline car so even after removing the key out of the ignition lock engine was working. Because the diesel engines are shut down by vacuum (not electically like gasoline engines) all the lights come on because the 15th circuit is stuck. It begins in the ovp.

I have just gotten back into town and will immediately check into these steps. I will try to disconnect those electircal items listed.

I will be sure to post my results as soon as they take place. I cant thank everyone enough for helping me with this very frustrating problem.

Thanks.

Does the OVP use a standard euro fuse, or does it use a blade type fuse. That will help me in knowing what to look for. Thanks.

The fuse in the OVP relay is Euro-type: it has 2 blades coming out and a thread inside the plastic(i am not sure if it's the the right name) but the fuse is not a round stick-type.

I think I found the OVP, it is located just to the right of the brake booster on the 87 300SDL as you had said. It looks like a recangular box with a flat 10amp fuse housed horizontally at the top of the device. The fuse is still good. When I pull the OVP out, should the dash lights turn off or is there something else that I need to do? Thanks for all of your help.

est, Thank you for the idea however, I have pulled the OVT out of it's recepticle and the warning lights still remain on and the several of the components under the hood continue to run. I will try working with the lock pump next.

Stevebfl, the car has an aftermarket alarm that was installed shorlty after the car was purchased (new is '87). The alarm was installed by a company in LA that marketed itself as an alarm installer for high end cars. There is no remote, the alarm arms when the doors are locked via the key. The alarm works with fuse 15 removed from the fuse box. I dont know if there is a factory alarm in the car.

Thanks again for all of the help.

If the problem hasnt disappeared after removing the OVP it is somewhere else. In this case i agree completely with steves thoughts on the problem. The aftermarket alarm could very well be responsible for your troubles.

If the aftermarket alarm still works with fuse#15 pulled and pulling 15 kills the lights. I would say that the aftermarket alarm is not directly the problem.

The factory alarm is under the passengers floorboard. Pull the carpets and remove the wooden or plastic floor panel. The alarm unit is to the center, it is black, it should have two connectors on it, and probably will say "Becker" on it. Try unplugging it. If that still has no effect, try to find the pump for the door locks and unplug it. It should be in the sparetire well encased in black foam. It could be under the rear seat, I just don't remember.

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

stevebfl, I just pulled the floorboard panel and found the boxes you described. The location seems to be a little different however. When looking directly at the panel there are three boxes, 2 silver and one black.

The 2 silver boxes are marked "Bosch" and each have one connector. One silver box is larger than the other and the larger of the two is situated towards the center of the panel.

The black box is labeled "Mercedes-Benz" and is the largest of the trio. It has 2 connectors and is situated to the extreme upper left of the panel. Is the alarm box, or could my car have not had an alarm?

It does not look like anything has been removed from the panel as the entire panel appears to have no extra holes or unconnected wiring harnesses.

Thanks, and I look forward to your reponse.

I just pulled the lock pump and the factory alarm box (at least what I think is the factory alarm) both of which did not rectify the problem.

I really appreciate everyones help with this problem and if anybody has any other ideas they would be much appreciated.

Thank you very much.

I wanted to thank everybody who responded to this post for all of the great ideas. Today the problem was resolved! I took the car to a local repair facility and they were able to diagnose the problem quickly. It turns out the number 6 wire to the fuse box was being energized all the time. It should only be energized with the key on.

In any case, the shop was able to quickly diagnose the problem because with everyones help I was able to rule out many of the potential problems.

Thanks, again, to everyone who took time to post here and help. I really appreciate all of your help.

Happy new year.

What was the cause of the #6 wire being energized and what did the shop do to remedy your problem?

Inquiring minds want to know.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

.

I just got off the phone with the shop. They said that the wire going to number six was making contact with a hot wire somewhere in the box. They just replaced faulty sections of wire and the car funtioned normally, as it once did. They also said that a piece of metal from a preiously blown fuse may have lodged itself inside the fuse box and made contact between two posts, which most likely led to the problem.

It turned out to be something that I never would have thought of. Again, thank to everyone for all of the ideas which in turn certainly saved me hundreds of dollars in diagnostic time.