Will a 4.7K potentiometer dim an LED or other bulb in a 12V DC circuit?

The only thing I need the pot to do is indicate the relative position of the motor(s). I plan to use a reversible polarity momentary switch for each of the three motors. I think it is OK to keep the power on for a bit after full travel is reached but not for too long, thus the LED to indicate when I'm at the end of travel.

Perceived LED brightness will give, at best, only a rough indication of pot position, because of apparent/actual brightness varying according to (a) ambient light level (the LED will appear much brighter at night than in the day), (b) supply voltage (unless you use a voltage stabiliser), (c) LED age (LEDs dim with age).
How quickly does the valve/drum move? If only a fraction of a second from one required position to the next, then won't use of a momentary switch to set the position accurately be rather fiddly?

carwhisperer said:

The only thing I need the pot to do is indicate the relative position of the motor(s). I plan to use a reversible polarity momentary switch for each of the three motors. I think it is OK to keep the power on for a bit after full travel is reached but not for too long, thus the LED to indicate when I'm at the end of travel.

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This likely will not work real well for the reasons Alec mentions. Using the intensity of a single LED, which as Alec points out will not be a constant simply isn't a good way to go. While I can appreciate your restraints of space LED brightness may not get you what you want. How close does this have to be?

Ron