Electric (mainly) tailgate problems anyone?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, Oct 8, 2002.

  1. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
    Likes Received:
    Roy WA
    So my key wouldn't roll my window up or down, but the inside switch worked. Time to tear the gate down, and figure out how everything works, and fix the problem. Anyone having problems with the rear gate, this might help.

    Open the gate. (if possible : )

    Disconnect the wiring plugs from the body to the gate at the back of the truck. Make sure ONE of the wires has 12V constantly. If none of them have 12V, (my 12V feed is an orange/black wire) then your tailgate won't work, and the problem isn't in the gate. Also, that will prevent you from blowing a fuse or fusible link (think the gates may be on a breaker later on) if there is a short.

    Remove the inspection cover.

    I was using my "house socket" set, so I'm not sure if 10MM or 7/16th is correct, most of the sockets are pretty much cheapy worn out ones.

    Right dead in the center is the unlatch mechanism. Notice running from the bottom of the latch mechanism, then a short way towards the drivers side, then turning down towards the base of the tail gate, the thin metal rod. It passes through a nylon/steel bracket bolted to the tailgate with two 7/16 or 10MM bolts which are normally covered by the inspection plate. There should be a small spring pulling UP on this rod near the unlatch mechanism.

    This rod "tells" the unlatch mechanism if the window is down or not. If the rod is not depressed by the lower edge of the window (really the track the rollers ride in) the latch will not work correctly, making it hard or impossible to open. The spring pulls the rod back up as the window is rolled up, if the spring is broken, the gate could be unlatched with the window up.

    Take a flashlight and peek through the inspection holes, up to the drivers side top latch inside the gate. The wires are running to the window latch switch, which cuts the power to the motor if the gate is open. If this switch is malfunctioning, either the window won't work from inside the cab or key, or it may work intermittently. You can pull the two wire connector off of the switch and jumper it if need be, make sure to leave no bare wires. After this "mod" don't forget when the gate is open!

    Unfortunate discovery here, the glass "down" height is *not* adjustable on this tailgate. The "guide" for the bottom of the window/unlatch rod is tack welded into place, and serves as also the "bottom" of the windows travel. The "guides" are bent at a 45* angle, and are quite thick and stiff. Bending would be pointless since they are already almost touching the tailgate outer skin, and if they break, the tailgate is pretty much worthless...the glass would fall right into the tailgate, I kind of doubt the glass is designed to go that far down. I'm stuck with about 1.5" of glass sticking out all the time. : (

    Now to get at the key mechanism. You've likely already noticed the window motor with the cable running from it to the regulator assembly. You can disconnect the cable from the motor if you like, and chuck the cable in a drill. Use low speed. That way you don't have to try and manipulate the switches if you are by yourself.

    There are 4 7/16 or 10MM bolts holding the regulator assembly to the tailgate. 2 on the drivers side, 2 on the passenger side. They are almost directly opposite each other. Drivers side bolts are easy to see/access, but leave them in place, tackle the passenger side top bolt first, as its hardest, and the window has to be almost fully extended to reach it. If the tailgate is in good shape, the window can be CAREFULLY fully extended and left like that, however, a seatback with some rags used to adjust height will give it some support if you are afraid of it breaking.

    Once you get that bolt out, do the other passenger side bolt, then the two drivers side bolts. You will have to roll the window back down, to access the other passenger bolt, then up for the drivers bolts. At least it will make it easier on you if you can move the glass.

    Once the regulator is loose, you can move the entire glass/regulator assembly "down" into the tailgate, enough so the two nuts (7/16 or 10MM) on the key switch housing are visible. You may have to roll the window some, push the entire glass/regulator assembly into the tailgate a bit, and keep doing this, until the nuts are exposed. Don't force anything, but the glass isn't extremely light, so just use your best judgement. Too much force, and you'll likely break the window.

    Once you get the nuts off, you should be able to pull the key housing off from the outside. (leave the gate open!) there should be enough wiring slack to pull it free from the gate, then disconnect the wiring. Mine used a plastic/metal nut to retain the wire connector to the switch assembly. If not enough wire slack, look over on the drivers side, and disconnect any wire retainers that will give you a bit more wire to play with at the switch.

    If you connnect the body to gate wiring now, and test voltage, the key switch connector hole the LONG pin fits through, (orange/black wire on newer ones) will be 12V constant. If its not, and you have 12 volts going into the gate, you have a cut wire inside the gate. If you do have 12 volts there, unplug the body to gate wiring, insert the key into the lock cylinder, turn it, and check continuity from the long pin to either of the two shorter pins. If no continuity from the center pole to one or both of the short pins, when the key is fully turned one way or the other, disassemble the switch mechanism (easy) and clean the copper contacts. Coat with anti-corrosion, grease, and you'll now have continuity with the key turned fully in either direction. There is almost nothing physical to fail in this switch.

    Now, if you have already disconnected the window motor drive cable, try plugging everything back in (before assembling to the gate) and see if the motor spins both directions, when the key is turned either direction. If it does, great!

    BEFORE reassembling the key housing/mechanism to the tailgate, turn the key, and with the window motor turning, wiggle the connector on the back of the key switch. You are checking for a tight fit from the connector to poles. If it stops running (move the wires slowly, or you may miss the motor "cut out" as the connection is momentarily broken) then you need to tighten the contacts in the wiring connector up.

    The black plastic wire connector (in my case) is not serviceable. The wires are "captured" and have a small metal U that is crimped to the ends inside the connector. each pin on the key switch is supposed to be gripped tightly by the U to make contact, but they loosen up. (as was my case)

    A SMALL flat blade jewelers screwdriver will fit inside the connector, and will allow you to bend the U shaped piece of metal a little bit closer together, providing a tighter contact. This completely solved my problem, even when wiggling the connector.

    There of course can be more things wrong (wires to window motor, etc) but I think I've covered most of the important stuff.

    I don't *think* I've missed anything obvious, but before delving into this project, if the tailgate does not work at all, FIRST check for voltage on the wires coming from the body to the tailgate...one should have constant 12V. If not, nothing else in the gate will work, and the problem rests outside of the tailgate! : )
  2. blk87K5

    blk87K5 1/2 ton status

    Dec 26, 2001
    Likes Received:
    Lubbock, Texas
    Wow that's a long post. I don't see how you could miss anything w/ that long of a post.
  3. OneInTheSun

    OneInTheSun 1/2 ton status

    Feb 17, 2000
    Likes Received:
    Pittsburgh, PA
    Dorian, another great post. /forums/images/graemlins/thumb.gif

    I just want to reiterate the "check the obvious" point. Two stupid reasons my tailgate has stopped working:
    1) Cut/crimped the wires when putting the tailgate back in.
    2) Forgot to clean off the overspray on the connections after painting.

    Somehow I always overlook the obvious, simple stuff. /forums/images/graemlins/crazy.gif

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