Hello everyone!

I was hoping some of you could help me diagnose/find a problem I am having on my 1980 450 SL. From my limited knowledge of cars and electrical systems, it appears to be a short or current draw, but beyond that I really have no clue. The car was my every day driver for nearly a year and a half, and I didn’t have any problems with it, but when I bought a new car the 450 sat for nearly 9 months or so – and that’s when the trouble started.

When I went to jump the car, it started…no problem at all. And when I drove it around some and tried to start, it seemed to start up just fine. I drove around for a few days with no problems at all, but then as soon as I let it sit for a day or two, the problem starts over again and the battery is completely dead.

I took it over to Autozone to have them do a systems test, and the battery and alternator seemed to be working just fine, so I believe my suspicion was confirmed…that I have something drawing on my battery.

The first test I did was disconnect the positive terminal on my battery and use a multimeter to see what as going on. The first few times I tried this I was showing a small current draw, which appeared to be 7 or so mA, with an increase to 10 mA or so every second as the clock was ticking, I assume.

I went to check and see if I could find which fuse was this was coming from, and when I did this, I got the same reading from the #1 fuse, and nothing from any of the other fuses, so it appeared that the culprit was the #1 fuse.

Then yesterday I went to check again and see if I could delve into the problem some more, and when I started working on it, I was getting the same reading, with nothing unusual going on. Then, all of a sudden, when I checked the #1 fuse, my multimeter jumped up all the way to the end of the scale, so I switched it to the 20 Amp reading but was getting no reading whatsoever. So I was getting a monster reading on the 500 mA scale, but none on the 20 Amp scale. At the same time, I noticed that the light underneath the glove box, that turns on when the door is opened, suddenly turned on when the passenger door was opened…Previously it had always worked for the driver’s door, but not for the passenger door. I started playing with the black switch on the door that depresses when the door is closed, and it looked like it was a loose connection, because depending on what position or angle I was pressing it it would turn on or off. The other weird thing about this was that when the door sensor WAS working, I was now getting a reading of about ½ amp or so on the 20 Amp scale (but when it wasn’t working, I was getting NO reading), but when I put it back on the 500 mA scale, it was still reading past the scale.

So basically, I still have no idea what is going on. I am assuming my problem is with the #1 fuse, but beyond that I really have no idea, or no idea where to start to look. I don’t know if the door switch has anything to do with it or not, or what to do test the other components. I know this explanation is long and pretty basic, but I was wondering if anyone had any ideas of what I may be seeing, or any suggestions for me to try that may be common problems on the 450sl.

ANY help that anyone can give would be GREATLY appreciated!