Without a correct diagram, you may need to physically check for power to the front window switch and see if any other wire gets power when you go to operate the sw..
You will either have power going out of the sw or not. If that is good follow that color wire to the other side of the hinge area harness to confirm power is going out the harness.. You should check for power to the driver's side motor with the sw depressed, If yes continue tracing , if not sw maybe defective. You could always jump the sw wires to by pass the sw and confirm .

 

Check the switch. Double pole double throw switch.
Both the master or driver's switch and the passenger's switch
See power going in and coming out
Then look for power and grounds at the window motor
The motor should have two wires going to it
Both should be held at ground.
Activate switch and one side goes hot
Depending upon which way the switch is activated will determine which wire goes hot
That also determines the direction the motor works.
If powers and grounds are good then must check the window regulators.
The regulators is the actual mechanism which moves the glass up or down

Note: checking electrical must be done with the circuit loaded

 

Thanks @avisitor and @hanky for your suggestions. Trying to do what you suggested I got stuck looking into it today by this rather strange behavior:

First: the battery voltage indicates 12.32V with engine off and 14.50 with the engine on. Is this normal? I'm reading about this showing the alternator as charging the battery.
Second: The voltage on the pins that go into the main switch is NOT stable. When I measured it initially I got "12V" (14V as measured) on pins 9 & 18 (per diagram below).
But a subsequent measurement got me getting 12V on pins 1, 5,6, 8,9 and 10.63V on pins 4, 14 (with engine off).
And then, with engine on I got the same (now 14.48V instead of 12V) plus two more pins at the "battery +": 10 & 18.

Then I noticed that if I move the wires the voltage goes down and up, and then sometimes it doesn't come up again.
The pictures below show where I measured and which part of the wires I was slightly moving around.

Does this mean the wires are faulty? A short would burn the fuses I think. All fuses are intact. Thoughts?
Thanks again!

Image 1: driver door with panel off.
Image 2: wire diagram the closest to my model

 

Yes, battery voltage when engine is off. About 12.5 volts fully charged
Engine running then alternator voltage. About 14.5 volts charging battery.

On the connector, reading the diagram, pins 10 and 18 are power supply. (engine on)
Pin 15 is ground, usually for the illumination circuit. But, should also provides ground for window motor
The switch selects which circuit gets power.
ie, Front right window up pin 1, Front right window down pin 2
If measuring voltages and the readings change as you wiggle wire then connection/wires are suspect.
With engine off, the circuit isn't powered, sometimes.
Sometimes after turning engine off, the power will stay on until door is opened.
So not really a valid test.

Power readings at pin 1, 5, 6, 8, 9 are not suppose to be hot until switch selects them
And especially not when the connector is off the switch.

So as Hanky has said, the door hinge area is usually where the wires break and a good place to check
If you can then would also follow the ground wire and clean up the grounds.
Good luck to you.
Hope you find the solution and come back to post the fix.
Others could probably benefit from your work.

 

My connector has the GND on pin #13, not #15 as in the diagram. This tells me I don't have the right diagram (and I've searched hard for it; even paid justanswer.com to get one. Side note: they were worthless & I got refunded).
But with the unstable voltage, this is a moot point for now.

Wiggling the wires in the door hinge is not affecting the voltage readings on the adaptor. Makes me think the wire problem (if there is one) it's not there, but right in the area shown on my pic.

Not sure what you mean here; this is what I've done:

• checked the both the battery GND and (+). Both are clean. No corrosion
• checked continuity between battery GND and car frame. It's solid

Anything else I should be doing? A quick google search didn't reveal other potential things to check.

I'll definitely share the final resolution.

Right now I'm actually planning to take it to an auto electric shop; the wiring fix is probably better done by them.

 

Okay, pin 15 is not ground but on pin 13.
That ground is taken from the chassis instead of running wire all the way back to the battery
It is probably there that may be a ground issue.
And yes, you are right. The problem is where the readings change when you wriggle the wires

Yes, auto electricians have the proper schematics and will know where to look.
Hopefully they will have an easier time figuring this out.
Good luck.

 

The most surprising resolution of all (although I fear it may be temporarily): at the suggestion of my brother I did a computer reset: took off the battery (+) for 45 min.
Once I reconnected the battery I checked voltage on pin #17 and it was still fluctuating as I was moving the whole wire harness around.
But I reconnected the door panel and surprise: the power windows work now.
I have no explanation why I'm seeing those voltage fluctuations, so I still plan to go and at least talk with a mechanic. Maybe it's my voltmeter? (highly unlikely, it's brand new, yet possible)

 

Works for now.
Hope it stays that way.
And thanks for the update