Electrical problem

[Mark280SL]

I seem to have an electrical problem with my 70 280SL.  I first noticed the dashboard light that comes on when you open the door flickering when I was driving the car, then eventually it stayed on continuously while driving.  I then noticed that when opening the door ( either door) engine not running the dash light comes on and I hear a sound the same as you would hear from the fuel pump when turning the key to prepare to start the car , closing the door will then stop the sound and the dash light goes out, again the car is not running when i observe that. The car starts and runs fine but the battery is no longer charging, I know this because the battery keeps going dead.  I have also noticed that if the car is running and the door is open and I turn the ignition off and remove the key the engine will continue to run until I close the door.

It would appear I obviously have a wiring problem or maybe the generator has just gone bad? but I'm not sure where to start.

**UPDATE** Gentlemen thank you for the pointers. It appears the rear sensor in the brake fluid reservoir went bad and is the cause of the problem. When I tried to buy a single sensor several online suppliers said they had them but many did not actually have them and it turned out you can't easily buy a single sensor at a reasonable price if at all from many suppliers. I found a seller on ebay that sold me the complete reservoir with both sensors included along with the caps etc for $109.97 with free shipping which was 50.00 less for the same ATE part then some other places so, it pays to shop around a bit. Thanks again to those who responded.

[Cees Klumper]

Hi Mark - search the forum and others do chime in, but I seem to remember something about the low brake fluid warning circuit being able to cause symptoms like this. Also, electrical gremlins like this can be caused by bad ground /earth. If the battery is not charging check the ground cable; I would check as many grounds as I could identify.

[Jonny B]

Try searching "door open light" you should find a number of threads to help explain this bit of an oddity about the set up on the 280 SL.

[glenn]

Is this the infamous 'low brake fluid level' problem?   Raise the contacts and see what happens.....

[Garry]

It certainly sounds like the problem.

 Open your brake fluid reservoir and take out the float and see if it has fluid in it from a pin hole.  When it drops below a certain level it will cause the light to come on but it also causes the petrol pump to go when you open the door when the car is not on.  A quirk of the Pagoda.

Garry