Does anyone know EXACTLY where the ground is for the switch? I tried finding it last night but came up empty handed. Pulled off the dash cap so I could see the wiring and the ground wire just disappeared into a big brick of wires and went off into obscurity.

 

The harness I can offer is the one that begins at the L/R taillight assembly area and goes to the tailgate motor. This harness also includes the feed wire for the defrost circuit. This harness btw has a crack in the insulation that I have somewhat repaired enuf to work as is (in fact I will have to remove it from my 86 in order to send it to ya). The ground itself is a screw to the body inside the left taillight .

I must admit to wire this in you may have to see if your Bronco came with the plug and harness that the factory switch needs to attach to. I have this as well, along with the feed wire to the rear of the rig but I probably can't provide that right now.

Of course Steve83 on super-motors is the go-to source for the wiring details...an excellent primer for the repairs on the tailgate..I'm sure u have the links, if not...here ya go

Here's a great pic as well ...

 

I had the exact same problem with my '96. Last year I bought a non-OEM motor(it was made in China unknown to me when I bought it) and all new rubber. I had a body shop here in Garden Valley, Idaho(near Boise) and it would go down, albeit slowly, but wouldn't come all the way up. They put the old motor in and it went to the top, but slowly. We then put the old rubber back in and it went up faster but not that fast. So, in the end I have the same old stuff. I did spray some silicon on the rubber and it worked some better. The door windows rock, but that rear window is a PITA for sure.

 

I'm wondering if I just got a cheap motor from O'Reilly.
With the weatherstripping out, it does zip up and down pretty well though. It really, truly does come down to binding with the weatherstripping.

I have a new piece of glass that I'll be putting in. I'm curious what difference it'll make. The piece I have now bows out in the center, which is what's causing it to bind. Just eyeballing it, the new piece looks much straighter, but I won't truly know until I get it in.

 

I think I've heard about JGBs weather stripping being too big/fitment issues before, but I tried searching for the post, and I can't find it. Have you compared sizes of the new and old stuff?

 

Unfortunately, the outer strip was missing since I got it, so I have no comparison.

 

Number one thing I'd do is add a new ground wire to the T-Gate. All this old wiring is developing crevice corrosion in the crimp connectors and in the in-line splices. The OEM ground is on the drivers side of the T-Gate. I'd add a brand new one on the Pass side. Say number 10 wire with soldered lugs. Try to find fine stranded wire if you can (?) and clean the treads on any bolt you use to establish this circuit. Use never-sieze on the treads.

Once you have 100% ground and the right glass, I'll bet it goes up/down just fine

Up front I add a new ground from battery (-) to the radiator support and to the main body. Same thing, #10 wire and soldered lugs. I go from a longer bat (-) clamp bolt/nut to the 6mm bolt holes right in front of the battery tray on top of the rad support, and to a pass side hood hinge bolt by running in behind the top fender lip. I have found this to be very helpful with all sorts of accessories.

To make the motor a bit better on cold start/high idle, I run a dedicated ground (new) from a bolt on the throttle cable plate on top of the manifold to the driver side hood hinge bolt. Same deal soldered lugs. All up, these new (fresh) ground paths really help make the systems more responsive and the ECM's job easier

 

Hey brocluno, thanks for the tips.

I don't know if it's different on later years, but on this model, there is no ground for the motor in or around the tailgate. There are two wires that run from the motor up to the front dash switch, and then the ground goes out from that switch. I just couldn't find where it ran off to and grounded. However, I did cut into it and add a new ground.

I've done a lot of extra ground work on this since I was tired of a lot of things having bad ground issues. I have extra grounds running from the battery to the radiator support, fender, engine, firewall, etc. to really help it out. It's aided in a lot of other areas.

The irritating part is, the sluggish performance with the motor is with the truck's battery removed and in the cargo area. I had cables connected directly from it to the motor, and that's how it responded. I wasn't using the switch in the video I posted.

Unfortunately, it's getting down into the 20s and a little bit too cold to go out and screw with it for hours on end.