Tailgate on my 96 bronco will only go up/close but if I switch polarity on motor tailgate will only go down/open. Key switch on tailgate and dash both operate the same, one direction only.
Fuse 12 and 14 CB are functioning. Constant power to tailgate switch was working so I jumped constant 12 v from fuse 5. Tailgate window motor is new. Grounds are dash are good. What possibly could be issue?

 

I have had to work on nearly every one of my Bronco's tailgates.
I thought the reversing of polarity was how the motor went both directions.
Found this in case it helps.

 

What I mean by reversing polarity on window motor is physically switching leads to motor then window does go up but not down from either tailgate or dash switch.

 

Latches…

So you are bypassing the switches (dash/ key) and applying power directly to the window motor? Is the tailgate open or closed?

 

I deleted the tailgate safety switch so that is not an issue.
What I did was run a separate ground wire from pink/grey wire on tailgate switch to chassis and switch works both up and down. Only issue is dash switch not working.

 

There are limit switches inside the tailgate
Those limit switches and the safety switch control the motor function
Fixed about a thousand and the limit switches were getting hard to find even in 1997
You put a garbage can under the window with a towel on it with the tailgate down (to support the glass while you test and replace the limit switches)
Pushing the limit switches with a long screwdriver will allow you to force the window up and "out of the tailgate" and onto your garbage can (glass will be completely out of the tailgate)
Then you can replace the limit switches while the glass is out
Then reinstall the glass

 

No idea why you would do that.

Have you checked the wiring between the body and tailgate for broken or frayed wires?

 

Where exactly are the limit switches located?

Thanks

 

The ends of the tracks, follow the wiring
They are behind the glass
That's why you need to shoot the glass up and out to check and replace them