Power window issue persists after motor AND switch replaced (2 Viewers)

[thisisjuan]

I know there's several threads about this topic and they've been very helpful in helping me navigate this, but I have specific questions about my situation as I'm at a loss of where the issue could be. Hoping to get some clarity! Here goes:
1990 FJ62.
Driver window goes down but does not go up unless trying the switch several times until, if you're lucky, motor engages.
When window doesn't go up I hear the switch/relays clicking. Switch is OEM that was replaced a few months ago. When I first installed it, the driver window worked fine for a couple of days, then this issue started.
I tested the switch with a light tester and I do get light when testing / pressing driver window switch up, which tells me switch is working fine (I know very little about this stuff so please correct me if I'm wrong).
So that left the window motor as the apparent culprit. So I replaced the original window motor with a new one and when I go test it, SAME SH*T. Down but no up. I'm so mad.
Now I'm thinking something with the connection for the window motor on my harness might be wrong. Any clues?

 

[89BIGBLUE]

You could check the wiring harness at the door hinge area. Might have a break/short?

 

[tmxmotorsports]

Check to see if the other side of the wiring to the motor has ground when pressing up on the window switch

 

[thisisjuan]

So I did a resistance test on the ground on the A pillar and I'm getting a pretty high reading - between 4.5 and 5.1 (all with the help of Google Gemini cause this is my literal fist time tackling any of this with any car ever and most of what I'm discussing here I am learning in the last 24 hours. I'm gonna try to clean that A pillar connection as best I can but boy is it hard to access.

@tmxmotorsports by "the other side of the wiring to the motor" do you mean the connection to the motor that comes from the wiring harness? and to do that does the car need to be on or off?

 

[tmxmotorsports]

I'm saying when you test for power upat the motor it may have power but no ground. Test motor when hitting the button one side of the motor will receive power the other side will receive ground

 

[thisisjuan]

So I tested both cables in the motor connector on the harness, and the black one gets close to zero either up or down, while the red one does close to 12 and then 0 (which is what should happen as far I understand). The black one intermittently gets voltage, like sometimes it seems to make contact but for the most part doesn't.

I wonder if the switch may have anything to do with this or if I should suspect the black cable on the motor connection is to blame. I keep taking more and more stuff apart and I'm not getting to a solution.