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1998 Mercedes-Benz SL500 Question: Power seats only work with a door open. Cig lighter fuse blown. replace, now OK

 

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MarksSL500, Brighton, MI, November 26, 2012, 07:45
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The cig. fuse blows (there is no element in the lighter), then the power seats only work with one of the doors open

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  • Answer #1

    your.mechanic November 26, 2012, 08:34
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     Master

    possibly a short in the electrical circuit.

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    MarksSL500, November 26, 2012, 09:11
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    wow, how insightful...

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  • Answer #2

    ziptie12 November 27, 2012, 04:56
     Master

    Does it matter which door is open?.........Do you have a circuit diagram and description??? What does the lighter have to do with the seats , and what does the door(s) wiring have to do with the seat??? Insight into these inquiries will undoubtably lead to more insightful solution(s). My suspicion is broken wire in door harness , that makes some contact when open -to complete the seat circuit , and at some point when moving door to close/open , it's causing a short-to-ground , blowing the fuse. Please let me know if any of this made sense and was the least bit insightful. Good luck.

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    MarksSL500, November 27, 2012, 05:50
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    I am attempting to get an electrical schematic. Its quite odd that the fuse for the cig lighter blows, yet has nothing to do with the seats. I bought the car in Texas and drove it back to Michigan. In Texas, I noticed that the power seats would only work if either door was open. It doesn't matter which door is open. I checked fuses and found the cig lighter was blown. I replaced the fuse and the seats operate with the door closed. I plugged in my Phone/Nav system and drove 1200 miles. No problems. Once home, I had my wife do some seat adjustement reprograming which worked fine (Seat 1, 2 and 3 respectively). A couple of days later we went to take a drive and the seats would work until the door was opened. I checked the cig fuse, and it was blown. There is no heating element in the lighter.

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    ziptie12, November 27, 2012, 17:03
     Master

    IF replacing the fuse for the cigarette lighter makes the seats work , then they have a power source in common somewhere.Maybe the power outlet (lighter) is defective, if there is nothing in it , or if it blows the fuse when the adapter is used then it's possible the adapter is in someway incompatible with it. Maybe easiest to 'remove' it from the circuit (unplug) for a little while to eliminate it as a cause for the fuse blowing. You also stated that the seats worked at some point , with the doors closed. IF that remains the case , then at this point , that would rule out my theory of a broken wire in a door harness causing a short. Until you are able to get a schematic , stay aware of the conditions when the symptoms affect the seats (as you obviously have) and I'm sure that will help narrow the problem area down. Keep us posted I'm always curious as to the final outcomes of these things , but people rarely tell us because 'it's fixed now, why bother' , I guess. And I like to know if I'm actually any help.

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    MarksSL500, November 29, 2012, 03:58
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    What's odd is the lighter receptacal worked fine for 1200 miles with my Phone/GPS plugged into it. And I purposely did not put the heating element back in the ligter when I uplugged the phone. During the road trip, I probably opened and closed the doors a dozen times between fuel, rest and sleep stops. When I got home, I had my wife adjust the seat/mirrors to her liking and then programed button number one for her setting. I then set up my seat/mirror prefernces, and programmed number two. We drove around a little, then parked the car in the garage for a couple of days. When we went to drive it again, the seats would not work unless a door was open, and the cig. lighter fuse was blown. I definitely need a schematic.

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  • Answer #3

    kylesl500 December 06, 2012, 22:25
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    There is a fuse that is blown. I had the same issue on my car checked the fuse and that was the problem. Also you seat heaters aren't working either I pressume. Check the diagram in the fuse box to find out exactly which fuse it is. If memory serves me correctly its a 15amp fuse. Hope this helps.

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