I came across this in relation to "Reduced Engine Power" because there were a lot of videos about the engine being artificially crippled by the software in response to some problem. A lot of people replaced the throttle body, some found wiring to the throttle body had a broken wire, bad ground, et al.
One of the iterations has a 4 wire potentiometer - +V, Ground, Pot 1, Pot 2. If there is a disagreement between Pot 1 and Pot 2 voltage the software cripples the engine. Another iteration uses 6 wires, 2X V+, 2X Ground, Pot 1, Pot 2, so that losing a ground wire or a V+ wire can allow the computer to continue in "Reduced Engine Power Mode." I think the 4 wire is a cost-reduced version of the 6-wire.
My interest is in the 4 wire version, which seems like it should be simple, except the wiper doesn't have an external connection and the layout of the wiper has 4 segments. The video that shows a teardown is: https://youtu.be/C5BEPmFB6cw?t=113 The view is only for a short time and it required me to freeze it pretty often to see that there are four tracks of resistor. I had to set the video to 720P. This is the clearest spot I can get is just after https://youtu.be/C5BEPmFB6cw?t=118 (YouTube doesn't capture a frame #)
The first link should start about 1 minute in and the author moves the unit around to show a little bit, but not a 100% clear view of the printed resistors of which it looks like there are 4 segments. It looks like there are also two smaller resistors, possibly for matching purposes. Near the end of the video he shows the minuscule brushes, of which one has what look to be defective finger.
What I am trying to understand is how the brushes pick off the voltage and return the signal. I see gold arcs but it seems unlikely the brushes run on them. I think part of the layout is to put each short arc of resistor in series with a long one so that the difference in radii and therefore resistance difference is cancelled out, allowing each path the have the same overall resistance.
I've spent a half a day looking for patents on redundant potentiometers, for potentiometer design, et al, but I don't see this configuration, The main sticking point is that if the gold arcs don't return the voltage, and the brushes don't have leads, then how does the voltage get back, and if the gold arcs do return the voltage how is voltage applied to the segments?