Keep Blowing the MBEC 1 50 Amp Fuse

Discussion in 'GM Electrical Tech' started by SpencerHouse, Nov 15, 2012.

  1. SpencerHouse

    SpencerHouse New Member


    I am new to the forum but need to get my problem resolved. I own a 2007 Chevy 2500HD Duramax, 4x4, CC, SB Vehicle Ident No. 1GCHK23D37F130823. For the past 2 1/2 years the truck periodically blows the MBEC 1 50 amp fuse that is in the Fuse box under the hood. When blown the two passenger side window, both power seats and seat heaters become inoperative. When replaced, the fuse will last between 1 day to 6 months. Have taken it to two different Chevy Dealerships, once while the fuse was blown and once not. Neither dealership could find a cause.
    Do you have any suggestions as to what would be causing this problem and/or how to correct it?

    Thank you,
    Daniel Spencer
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    My friend has a 2004 Silverado and had the same problem. I found a wire rubbing on the edge of metal grounding out left of the brake pedal by the parking brake pedal. It was on a white plug coming out of the mbec that has a cover on it. I would suggest looking around under the dash for wires rubbing on metal edges

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  3. SpencerHouse

    SpencerHouse New Member

    Thanks Pikey, I certainly will check that area out real through. What made you look in that area?
  4. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Your issue is definitely intermittent (well duh :) ). Unfortunately, that makes it much harder to diagnose unless it just happens to be broken right when you're diagnosing it. I would also agree with Pikey in that I'd look for cut or chafed wires. Does this issue mainly crop up during certain weather events such as hot, cold, wet, etc? That will also help you get some insight as to the source of the issue.
  5. SpencerHouse

    SpencerHouse New Member

    There don't seems to be any pattern to weather conditions. We have on several occasions reframe from using the seats or windows for an extended period only to try the window and find it blown again. Can't find any common denominator.
  6. RayVoy

    RayVoy Epic Member 5+ Years 5000 Posts

    Past experience stories can be a big help with this type of problem. Like [MENTION=51590]Pikey[/MENTION], and his helpful story, I had a friend with a similar problem, in his case, there was a wire grounding under the power seat.
  7. SpencerHouse

    SpencerHouse New Member

    Your Right! That's the problem... way too many places that it could be grounding out. I read some where that one of the electrical motors could be arching. The possibilities are endless. Mean while I have a wife who can't drive without re-adjusting the seat and with winter coming on....can't turn her seat warmer on.....not a happy camper. I will try and check out Pikey's theory tomorrow.
  8. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I know that this might sound strange, but when I was looking for my friends issue, I started running my hand over spots where wires went across metal corners, I cut myself on the spot where I found his rubbing.
  9. SpencerHouse

    SpencerHouse New Member

    Does this mean I need to be willing to sacrifice my blood to find this short? Maybe a little!
  10. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    Yep!! It's all for the good of your Chevy! This problem has one advantage, your wife can not drive your truck, but it is outweighed by the disadvantage of not being able to turn on her heated seat.

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