Sorry Snulma1 unfortunately I don't know anyone in your area that could help.What does "R" have to do with things? That's the rear tail lights which, I believe, work fine. I though the issue was the instrument cluster lights, which is "I", and which the OP already tested, above and which stop working with the switch in the "HEAD" position even though a "bench test" shows continuity.
To explain my comment, voltage on a line can interfere with taking an ohm reading therefore I stated to disconnect the power source. With the circuit breaker shut points A and B are the same electrically. With switch in park position, arrow straight up & down, power moves from switch to the right to R (tail lights) and up to the rheostat to power I (instrument panel). With the switch in head, arrow at about 225 degrees, power enters the part I highlighted before splitting to the tail lights and instrument cluster. However, Woodchuck is correct that if there something wrong in the highlighted portion you would also loose your tail lights.
If it's not a distraction, start the car and perform the following; with switch in park measure voltage between ground and I then measure same with switch in head. Do the same measurements and switch positions between ground and R. Because the instrument cluster goes through the rheostat (relatively higher resistance), a ground on the highlighted area could cause a voltage drop so the tail lights work and the instrument cluster is not receiving enough power to see the lights through the rheostat.