'09 Box truck, no brake lights, help!

Discussion in 'GM Electrical Tech' started by H82typ, May 24, 2013.

  1. H82typ

    H82typ New Member

    :sign0016: Hi, everyone! :D Ok, I'm really sweating here! This truck runs 7 nights a week, hauling bread. Relief driver runs through a puddle, he thinks. A deep puddle. All the box lights go out. Tail, running, markers turn signal and brake. Apparently whatever happened blew all the fuses. He replaced them, got markers and tail lights back, No left turn signal or brake lights.Front flashers works normally, left and right, as do the hazards, so I'm assuming (for now) that the mf switch isn't bad. The wiring in this truck is NOT the way it is in the diagrams. The fuses under the hood list 1 fuse for each side on the brake lights, I'm only finding 1 fuse and a blank for the other side. My best guess, at this point, would be a BCM - because all of the circuits run through that... or an open between the chassis fuse box and the box(body) fuse box... or an open between the body fuse box and the brake lights. The wiring diagrams make mention of 2 solid state relays underneath the main fuse box which 'aren't servicable'... So, any ideas?
    *gets a 12 pack* Looks like I picked the wrong week to quit drinking! :erf:
  2. montyss

    montyss New Member


    check the connection box under the rear of the truck above where the spare tire would go for power into it , the front wire harness goes into it then the taillights and other rear electrical connections are made at it also . These go bad sometimes
    GM calls it a junction block
    Last edited: May 24, 2013

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