Phantom Electrical Problem
09-15-2005, 10:24 AM
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1995 S320 and 1995 S500
Phantom Electrical Problem
It's a 1991 300e having power failure. New battery, new alternator, Mercedes mechanic can not find the problem and insists it is an electrical problem. If we jump it, then it runs temporarily. Any suggestions would be greatly appreciated.
--G
--G
09-15-2005, 10:43 AM
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things with and without wheels
Need more info with the symptoms you are experiencing.When you say its loosing power in what way?car stalls?lights go out?car wont restart?
09-15-2005, 02:26 PM
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1991 300E
sounds like you have a parasitic drain on the battery. check for things like the antenna motor running. '91's don't have the infamous bad wiring harness, but that could be your problem.
09-16-2005, 12:24 PM
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Originally Posted by Gman91932
It's a 1991 300e having power failure. New battery, new alternator, Mercedes mechanic can not find the problem and insists it is an electrical problem. If we jump it, then it runs temporarily. Any suggestions would be greatly appreciated.
--G
--G
09-16-2005, 12:35 PM
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1995 S320 and 1995 S500
answer found in archives!
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Rafael Grullón
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I've got your solution!
My 1990 300E did exactly the same thing when I bought it three years ago. It was dissapointing to let the car rest overnight and find the next morning that the battery was dead. And the problem was that I checked the battery voltage with the car and everything off and couldn't see a drain...until after many tests and sleepless nigths, I checked the battery voltage WITH THE CAR LOCKED. Then the drainage was incredibly high.
The next step was to find where the drain was. So I dismantled half of the car to find the CENTRAL CLOSING SYSTEM BOX (I don't have the electical manual nor wire blueprints) UNDER THE REAR SEAT. It is a black rectangular box on the driver's side (left).
I opened the box and found a relay (1"X'1"X1") that stayed working after the car was shut down and locked. This relay closes the windows and sun roof when you lock the car. I took out the relay and the problem was gone.
Now I have central locking of the doors, but the windows and sun roof have to be closed "manually" (pushing the buttons I mean) if they were open when I'm about to leave and lock the car.
I know I have to replace that relay, but in my very hot weather country I almost never drive without the A/C, so the windows are always closed already when I park my car, meaning that I don't need very much the ver nice and convenient "total closing system". In fact I had forgotten this feature until now that your post brought it back to my memory.
Hope that this is your problem because is easy to solve changing that relay, and this, as happened to me, will bring peace for your mind knowing that your car will be ready after the overnight rest.
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Rafael Grullón
Almost a Member!
Join Date: Oct 2002
Location: Santiago, Dominican Republic
Vehicle I drive: E420 Sport
Posts: 33
I've got your solution!
My 1990 300E did exactly the same thing when I bought it three years ago. It was dissapointing to let the car rest overnight and find the next morning that the battery was dead. And the problem was that I checked the battery voltage with the car and everything off and couldn't see a drain...until after many tests and sleepless nigths, I checked the battery voltage WITH THE CAR LOCKED. Then the drainage was incredibly high.
The next step was to find where the drain was. So I dismantled half of the car to find the CENTRAL CLOSING SYSTEM BOX (I don't have the electical manual nor wire blueprints) UNDER THE REAR SEAT. It is a black rectangular box on the driver's side (left).
I opened the box and found a relay (1"X'1"X1") that stayed working after the car was shut down and locked. This relay closes the windows and sun roof when you lock the car. I took out the relay and the problem was gone.
Now I have central locking of the doors, but the windows and sun roof have to be closed "manually" (pushing the buttons I mean) if they were open when I'm about to leave and lock the car.
I know I have to replace that relay, but in my very hot weather country I almost never drive without the A/C, so the windows are always closed already when I park my car, meaning that I don't need very much the ver nice and convenient "total closing system". In fact I had forgotten this feature until now that your post brought it back to my memory.
Hope that this is your problem because is easy to solve changing that relay, and this, as happened to me, will bring peace for your mind knowing that your car will be ready after the overnight rest.
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Rafael
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09-22-2005, 10:07 PM
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1995 S320 and 1995 S500
under the seat window relay
Does anyone know the name or part number for the under the rear seat relay. My dealer parts guy does not know. My windows dont work but the battery does 
