Burban Tailgate - how to raise window with dead motor?

[swissarmychainsaw]

Hey everyone,

the motor on my 76 suburban tailgate is dead.

I hooked the battery directly to the wires leading to the motor (have had some issues in the past).

I get a little "click" from the motor but it no longer moves the glass up.

It is now stuck in the down position. how do I get the glass up to get to the motor?

Unbolt the window "sash"? The gold thing in this pic

[BlueJeep]

I don't know is the direct answer to your question. But, if it's anything like the doors (going through this now), if you unbolt and remove the motor the spring will hold it in the up position.

Oops, just re-read and see that you cannot access the motor with it down. Maybe this can help:

http://67-72chevytrucks.com/vboard/s...d.php?t=392118

[swissarmychainsaw]

Just ordered this:
https://www.oreillyauto.com/detail/b...ow+motor&pos=0

[kwmech]

Find a way to tap the side or end of the motor while somebody toggles the switch. This is why I have barn doors

[swissarmychainsaw]

Originally Posted by kwmech

Find a way to tap the side or end of the motor while somebody toggles the switch. This is why I have barn doors

To be fair the motor has lasted almost 50 years. that's pretty amazing.
The other thing is that I pooched it. The switch failed, so I bypassed it with a toggle. The bad news is I did not us a "momentary" switch and left it in the UP position which I think killed the motor.

Still trying to source one!

[swissarmychainsaw]

Ok So I actually have a motor coming, they are NLA and it was a pain to source one.

So now I'm for real going to have to remove the tailgate window and motor.

I have see where the rear spring is a problem and that you need to hold the regulator in place while you remove the motor.

Can anyone confirm?

Here's vid https://www.youtube.com/watch?v=5rqQq9Oj1eA

Note that burbans and blazers are different.

[SilverMiner]

Originally Posted by swissarmychainsaw

Ok So I actually have a motor coming, they are NLA and it was a pain to source one.

So now I'm for real going to have to remove the tailgate window and motor.

I have see where the rear spring is a problem and that you need to hold the regulator in place while you remove the motor.

Can anyone confirm?

Here's vid https://www.youtube.com/watch?v=5rqQq9Oj1eA

Note that burbans and blazers are different.

Have you solved this problem?

If not, removing the bolts which hold the sash (and therefore the window itself) to the regulator is possible by using a shorty 3/8 wrench. Once the sash and window are separate from the regulator it can either be fully removed or partially pulled out enough to access the regulator and motor. You don't have to worry about the spring under tension until you attempt to remove the motor. Edited to ad - once the window is out of the way, your options are vastly improved. You can remove the regulator and motor as a unit as long as you get the handle hardware out of the way and then properly restrain the spring before removing the motor.

Depending upon the condition of the rubber in the tailgate, you may not want to fully remove the window with the metal sash attached. It is not necessary as long as you have means to support the window with the tailgate down. Even with brand new rubber when I removed the window from my 1980 Burb with sash attached it caused minor damage. I can only imagine how the 40 year old rubber might have suffered. Edited to ad - Thinking about it more, fully removing the window may be required in order to get the regulator out with the motor attached. Can't quite remember.

[swissarmychainsaw]

Originally Posted by SilverMiner

Have you solved this problem?

If not, removing the bolts which hold the sash (and therefore the window itself) to the regulator is possible by using a shorty 3/8 wrench. Once the sash and

...

Thank you! I finally have a motor, but have not opened it up. This confirms my thoughts around how to get the window out! Thanks a bunch!

[swissarmychainsaw]

Ok I'm finally getting around to this.

Peekaboo


My bolts where 7/16 and were hard to get to but doable.



Off!



Now, can I remove the whole regulator as one unit?

[swissarmychainsaw]

I was led to believe this was under spring tension when the window is down, but the spring stayed with the tailgate and not the regulator!



Here I put a wire to the motor and hooked a Bat-tree to it.


And wouldn't you know it the motor moved!
Put the wire on the other lead, and it moved the other way. Man I think my motor is ok, and it's all that hinkey wiring (and dust) that's causing problem!

The dash switch has never worked, and My key stopped working to operate the rear window, so it's time to take that switch apart and figure out what's going on in there anyway.

[Irish1941]

Was spring under tension? Looks like from here in SoCal spring is off the stop on the regulator. Just got a '90 burb a week ago and same problem. Spring was over clocked and didn't work the window. Just curious at this point

[swissarmychainsaw]

Originally Posted by Irish1941

Was spring under tension? Looks like from here in SoCal spring is off the stop on the regulator. Just got a '90 burb a week ago and same problem. Spring was over clocked and didn't work the window. Just curious at this point

It was not under tension at all. it was just laying there when I pulled the regulator.

It did go up and down though, so clearly the spring helps but is not needed (?)

[SilverMiner]

Originally Posted by swissarmychainsaw

It was not under tension at all. it was just laying there when I pulled the regulator.

It did go up and down though, so clearly the spring helps but is not needed (?)

I'm pleased to see you're still here and making progress! I can't speak specifically to the 1990 version (I'm a 73-80 sort of fellow), but all of the other Burb tailgates I've messed with had the spring installed on the regulator. I'm quite certain it is absolutely necessary - the engineering gods at GM were never allowed by their bean-counter overlords to waste money on parts that could be eliminated.

I don't recall the exact method of installing the spring onto the regulator. I do remember it wasn't difficult but it did have some interesting moments where things going wrong could have been painful.

[swissarmychainsaw]

Originally Posted by SilverMiner

I'm pleased to see you're still here and making progress! I can't speak specifically to the 1990 version (I'm a 73-80 sort of fellow), but all of the other Burb tailgates I've messed with had the spring installed on the regulator. I'm quite certain it is absolutely necessary - the engineering gods at GM were never allowed by their bean-counter overlords to waste money on parts that could be eliminated.

I don't recall the exact method of installing the spring onto the regulator. I do remember it wasn't difficult but it did have some interesting moments where things going wrong could have been painful.

This one is '76

[SilverMiner]

Originally Posted by swissarmychainsaw

This one is '76

Well then there you go. The spring is absolutely required to assist the motor to raise the full weight of the window upright and overcome the seal resistance.

Examine the spring and regulator carefully to determine why it was laying loose. I would suspect something is broken, as it just isn't right. I'd be uncomfortable buttoning everything up not knowing why that spring wasn't where it belonged.

[swissarmychainsaw]

Removing the key switch:




I put a multimeter on it, and was able to register resistance across the poles.
So I think the switch is actually good (more testing after cleanup)

Anyone knows how this comes apart?
Or is there a better way to clean it?

[swissarmychainsaw]

Originally Posted by SilverMiner

Well then there you go. The spring is absolutely required to assist the motor to raise the full weight of the window upright and overcome the seal resistance.

Examine the spring and regulator carefully to determine why it was laying loose. I would suspect something is broken, as it just isn't right. I'd be uncomfortable buttoning everything up not knowing why that spring wasn't where it belonged.

So it should be under tension when in the down position, right?
I can raise the regulator to "way up" install the spring, lowering the window and winding up the spring? Something like that?

[Irish1941]

Originally Posted by swissarmychainsaw

Removing the key switch:



I put a multimeter on it, and was able to register resistance across the poles.
So I think the switch is actually good (more testing after cleanup)

Anyone knows how this comes apart?
Or is there a better way to clean it?

At that point, contact cleaner thru the key hole. Its a sealed switch. Looking at one now.
As for the spring, SilverMiner is correct. Spring needs tension. This 90 is first burb I've had in long, long time Im not parting out. I'll look in my books and see how GM changed the insides. Pretty sure power regulators stayed close in design.

[SilverMiner]

Originally Posted by swissarmychainsaw

So it should be under tension when in the down position, right?
I can raise the regulator to "way up" install the spring, lowering the window and winding up the spring? Something like that?

Yes, the spring is compressed in the "down" position. But installation is more complicated than you describe. If I remember correctly there are holes in the regulator gears that line up with holes in the main regulator - placing a screwdriver there secures the arms while the spring is installed.

I can't recall if I learned how to do it properly from a thread here on this site, a YouTube video, or from the instructions that came with a new regulator. Either way, I don't remember enough to give you a detailed walk-through via text I'm afraid.

[swissarmychainsaw]

Here we go then!

[IMG][/IMG]

[swissarmychainsaw]

Ok so here's where we are.

I tested the "Tailgate Keyed Switch" using a multimeter, and it tests OK.

I put power to both terminals of the electric Tailgate window motor and it turns both directions.

Today I dug into the wiring to see what was up. There *should be constant power from the Bat-tree to the "Tailgate Keyed Switch" on the Orange/blackstripe wire to the switch. There is none.

I unwrapped the wires in the Tailgate and they looked ok. So under the truck I went to see if I can a connection all the way up.

I traced the wires out of the Tailgate to the underside of the burb. Right away I found this:


I find the other side in the frame rail:


But there is no power there either. I thought I had a cheap win on my hands.
Nope.

So I follow this up the frame rail...


Until I get to the firewall. So far so good, everything seems intact.

No onto the INSIDE of the cab.
Right above the fuse panel I found ANOTHER plug, unplugged. This was the same Trio of Brown/Orange/Blue. Also no power at THIS plug. Sorry no pic.

I then PULL THE DASH.
Hyep.

So anyway.
Now I can see what's going on. Sorta.
I follow the three wires wrapped in a harness to a Tee - there is a small red wire also unplugged. The Tee Splits, to the switch, and to what I believe is a relay.




I pull the Dash Switch.


Test it using the Multimeter: It works


Switch Wiring - Red goes from switch to Relay, Blue and Brown go all the way back to the Tailgate.


So what is weird is how this set up GETS power from the fuse panel. No wires connect to the panel (or elsewhere) to get power. Just that thin red wire that I believe should be plugged into the fuse panel.

How do I test the relay? And why would the relay have such a little wire delivering 12 volts to the relay.
IS that actually a relay?

[swissarmychainsaw]

Here is a diagram of how this thing is wired.




But where is it getting power from the battery???

[SilverMiner]

Originally Posted by swissarmychainsaw

Here is a diagram of how this thing is wired.




But where is it getting power from the battery???

Attached is a portion of the GM Wiring Diagram specific to the rear window - it appears the battery power is sourced via the junction block on the firewall, found very close to the center under the hood. There is also a circuit breaker (unknown location, but I believe it is on the fuse block) which may be bad and denying your tailgate the power it requires.

User HATZIE has contributed priceless scans of GM manuals including a higher resolution PDF, the portion of what I've clipped. They can be found in this thread:
http://67-72chevytrucks.com/vboard/s...d.php?t=545416
The detail showing the power rear window circuits seems to be the next to the last page of the PDF - don't get cross-eyed trying to decipher the giant diagram in the middle.

[swissarmychainsaw]

Thank you. I just figured this out today.

Turns out the Orange/Blue/Tan harness that runs the full length of the truck plugs into the firewall just below (ish) the Master cylinder.

If you trace that Orange wire, it does in fact go to a junction on the FW in the same area (near the brake booster), you have to really look for it though!

I cleaned the plugs, and now I have power to harness under the dash.
Checked the relay (it's working)
Check the switch (working!)

So next up, plug everything back up and re-assemble the tailgate...

[swissarmychainsaw]

Well, it seems that the section of wiring running past the fuel tank is where it's bad.
The short version of the story is, I had to just cut out the section hidden in the frame rail by the tank. So I've kept as much wiring and stock plugs as possible and am going to tie in a section of new wire to replace the bad part.

There were some D rings holding the harness in place, and I could not access them without dropping the tank!