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Rear Electric Window

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Mastiff, Dec 29, 2003.

  1. Mastiff

    Mastiff 1/2 ton status Premium Member

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    My rear window is to the point where it will barely raise itself at all. When I press the switch, the interior lights dim while the window is trying to move. Whether the engine is running or not seems to make little difference, and I have two batteries (in parallel) both in good shape. The starter cranks like crazy, so I don't think I'm hurting for battery power.

    Any suggestions where to start looking first? I could swear I replaced the little motor only like 5 years ago or so.
     
  2. skratch

    skratch 1/2 ton status

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    Sucks, but it sounds like either the motor, or a bad connection most likely the ground.

    I'd check the wiring first, and if it's all good, then hook a battery directly to the window wiring in the rear and see if it does the same. If it does then the motor is most likely bad.

    That is all assuming you don't have any problems with the weatherstripping around the window. When mine got out of alignment the window was really slow because of the bind. By the time I fixed that the motor had gotten worn out and had to be replaced too.
     
  3. Confedneck

    Confedneck 3/4 ton status

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    are the window runs are dry and need to be lubed? use white lithium grease, or if you can, find some "mini-vent window lube".. you can buy that for sure at a ford dealer, we use it all the time..
     
  4. dodgedude99

    dodgedude99 1/2 ton status

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    what do you do when the key switch doesnt work and you know from testing that the switch is good?
    (sorry didnt mean to hijack the thread).
     
  5. JK5

    JK5 1/2 ton status GMOTM Winner

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    [ QUOTE ]
    Any suggestions where to start looking first? I could swear I replaced the little motor only like 5 years ago or so.



    [/ QUOTE ]

    It sounds like the motor is the problem...
    bad brushes or windings in the motor...
    First I would un-plug the harness by the t-gate..
    And TEST the motor with a ohms meter...
    making sure the motor is still good..

    But take the panel off...
    Can You smell any thing burning??? (Electrical smell)
    How do the wires look???
    Is the MOTOR grounded well?? (TEST)

    Good luck!!!

    GM had MEXICO make some motors....and they didn't last long.. I'd look there first!!! /forums/images/graemlins/wink.gif
     
  6. dyeager535

    dyeager535 1 ton status Premium Member

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    You say the key switch itself tests good, but doesn't work when installed? Does the dash switch work? If yes on both, then the wiring for the switch on the tailgate should be the problem.

    I had the above problem with my key switch, and after checking everything out very closely (had voltage to the switch, the switch contacts were good) I noticed that the plug that goes to the key switch, has springy metal connectors in it. One was bent, meaning no contact when it was plugged into the switch.
     
  7. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    are the window runs are dry and need to be lubed? use white lithium grease, or if you can, find some "mini-vent window lube".. you can buy that for sure at a ford dealer, we use it all the time..

    [/ QUOTE ]

    Are you talking about the runs in the topper, or within the tailgate itself?
     
  8. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Okay, before I can debug at all, I need to know how the system "knows" that the tailgate is open. /forums/images/graemlins/crazy.gif I can't seem to fool it into letting me test the window when the tailgate isn't closed and latched. Where does the motor derive its ground, is it by a wire, or direct contact? Maybe something got painted when I had the paint job done, ruining the ground.

    Thanks.
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    System "knows" because of the switch in the drivers side LATCH on the tailgate. You can reach in there and unplug it for testing, or just jumper the wires and leave it that way.

    The wiring changed at least once between 1981 and about 1985, because I had to deal with it. However, there may have been only ONE change between 1973 and 1991, although I wouldn't know it, as I don't deal with the pre-81 stuff.

    The "early" wiring uses round connectors, similar to the license plate lamp disconnect, the later stuff is weather pack. On my later one, there is a ground that comes out between the tailgate and the body (right where the plugs go together) that is grounded to the body.

    Doesn't exactly answer your question, but I don't have a wiring schematic to show you or go off of. /forums/images/graemlins/smile.gif
     
  10. skratch

    skratch 1/2 ton status

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    Just keep in mind when you do this to have someone or something to hold the glass as it comes out!

    I learned the hard way with my Burb!
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    The last time I did this I let it hang out there by itself, but I wasn't moving it or anything.

    Didn't have anything to prop it up with, but usually a chair or stacked boxes is a really good idea if the glass is going to be fully extended while you work on it.
     
  12. Confedneck

    Confedneck 3/4 ton status

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    talking about all the runs, in the door and in the topper, just not along the top seal because when that window rolls all the way down, it would leave a film all over..
     
  13. Mastiff

    Mastiff 1/2 ton status Premium Member

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    Well, I did some hacking on this problem. It looks to me like the way it work is this. Ignoring the dash switch for a now, the tailgate just requires 12V to come in. The 12V goes to the key switch on the gate and depending on the way the key is turned, routes the 12V either to the blue or pink wire (12V is orange). The motor has a connector with two conductors, the pink and blue, and one of them goes to 12V (relative to ground, not the other) depending how the key is turned. So, bottom line is that I think the motor must get its ground through the metal of the tailgate, not a through a wire.

    I ripped everything open and with the tailgate flat, the window was happy to open but had a heck of a time closing. I disconnected the drive cable from the motor and it spins like crazy either way. I then reconnected it and disconnected the other end of the drive cable and it still spins easily either way. With it disconnected from the motor, I can verify with a pair of pliers that it's easy to turn in one direction and not the other. Something in the gearing is causing a lot of resistance, especially going down.

    I pulled the little tracks off that attach to the bottom of the glass and they were pretty grungy. I scrubbed them out and lubed them lightly, but this didn't make much difference. I also pulled the little assembly that converts the drive cable to gearing, but I wasn't really able to get it all the way out. It was disconnected from the rest of the assembly though, and I could tell the motor was happy to spin this much either direction. So, the bind is someplace in the big gears and arms.

    Generally, there is a lot of sandy grit floating all over the place in the gate. I'm not exactly sure why, but maybe it's byproducts of my recent body work and paint job that found their way in there. It's working a little bit better since I was pulling stuff apart and oiling around, but it's still pretty slow. I'm considering opening up the access panel and pressure washing in there to blast out the grit and stuff. I'm not sure if this is a good idea since it might de-lube everything and the grit maybe be embedded in grease anyway.

    These things are kind of a PITA. If it was easy, I'd consider switching to a manual rear window instead.
     
  14. detailer03

    detailer03 1/2 ton status

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    When that happened to mine, it was the cable. The cable that goes from the motor to the gear box. The cable is like a speedo cable. It needs to be lubed, or replaced. BE CAREFUL. The window is spring loaded to go up. Dealers still stock the cable and so does LMC. If you have to remove that little gear box watch your fingers. To remove the cable from that end, you will need to sqeeze it and pull. When you look at it, you will understand what I am talking about.
     
  15. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    When that happened to mine, it was the cable. The cable that goes from the motor to the gear box. The cable is like a speedo cable. It needs to be lubed, or replaced. BE CAREFUL. The window is spring loaded to go up. Dealers still stock the cable and so does LMC. If you have to remove that little gear box watch your fingers. To remove the cable from that end, you will need to sqeeze it and pull. When you look at it, you will understand what I am talking about.

    [/ QUOTE ]

    Thanks, yeah, it took me a minute to figure out the situation with the cable. It seems like it's okay to me, but I guess it's hard to tell. How is it spring loaded? I had the window itself completely disconnected from the mechanism and nothing happened. But then if the arms are spring loaded, that would explain why it had such a hard time going down when the tailgate was down. The spring possibly just counteracts the weight of the window...

    I see the cables in LMC for $29.95, but not the motor, who has that? Dealer?
     
  16. frankin5

    frankin5 Super Mall Crawler Premium Member

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    /forums/images/graemlins/mad.gifmotor lo longer availible from GM new have to ge a rebuilt about 100 plus core.
     
  17. Mastiff

    Mastiff 1/2 ton status Premium Member

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    [ QUOTE ]
    /forums/images/graemlins/mad.gifmotor lo longer availible from GM new have to ge a rebuilt about 100 plus core.

    [/ QUOTE ]

    Lame. So where would a guy go to get a rebuilt? Not that I need one yet, but for future reference.
     
  18. Muddytazz

    Muddytazz 1 ton status

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    You can get them from LMC or Chevyduty /forums/images/graemlins/thumb.gif

    or a junkyard /forums/images/graemlins/grin.gif
     
  19. tungsten

    tungsten 1/2 ton status

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    I'm bookmarking this thread. /forums/images/graemlins/laugh.gif My '85 is doing the same thing but it's slow going up OR coming down and supposedly the window motor was replaced recently.

    The rubber window channels all look pretty ratty though, so that may be the deal. Not going to mess with replacing them until I have the vehicle repainted though. Will try a little white lithium grease in the channels until then.
     
  20. rick88blaze

    rick88blaze 1/2 ton status

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    autozone listed the motor for about $60 with core exchange. /forums/images/graemlins/thumb.gif

    does anybody know where to get the little plastic rings that go in the tracks that bolt to the window sash? /forums/images/graemlins/1zhelp.gif
     

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