long story short - M and S modes blink when driving over 75 mph when the temperature is over 75 degrees. Made a 1500 mile trip keeping it at 70 -73 mph without incident. Code that is given is P0705 - Transmission Range Sensor.

Longer version - Drove our Disco II to Florida from Wisconsin. Left at 6am and got to Nashville by 3pm. Stayed over night and left at 7am the next morning. All the way to Nashville we experienced normal operation - 150 miles outside Nashville (when the heat started to reach upwards of 75 degrees) the M and S lights came on. Pulled off highway and started googling. Most posts on here indicated battery or alt could be cause, so I tried to start it back up and it turned over like normal. Put it into gear and everything seemed fine. Made it about 200 more miles and BAM, M and S again - exited the highway and started checking fluids - oil was a tad low so topped it off. Found out an Orielys was on the same exit so drove there to get codes read, also batt and alt tested.

Battery and Alt tested fine - code was P0705 - Transmission Range Sensor Circuit Malfunction.

I was fully prepared to pay for the X,y,Z switch to be replaced - but no local mechanic would be able to touch it for over a week. Needless to say, we weren't willing to sit by in backwoods GA to wait for this repair. We decided to keep going getting 2-300 miles before having to pull off and restart. with only 400 miles left to Tampa we were on our way.

Arrived in Tampa - Again attempted to contact local dealer for service and various other import specialist and transmission shops - no one could fit us in until the following week. Decided to keep driving it around town while keeping an eye on performance, gas mileage and what not. Everything seemed of and no m and s lights for the week we were there (didn't go over 65 in the city).

Left Tampa for Wisconsin at 8 am, decided to keep speed at 70-73 MPH on our way back - no issues unless we had the cruise control on, or let the speed get above 75 (hard to keep it slow). When lights came on, we just pulled over and shut it off for about 15 minutes and then carried on.

This is where it gets odd. We drove straight back - no hotels. 24 hours straight. After we got further north, apparently i wasn't paying too much attention because I realized I was going 82... no lights, nothing. Only thing that changed was the outside temperature. it was hovering around 58. Kept speed up around 80 for the rest of the trip (500+ miles) and no problems. Cruise Control on, no problems. Now the truck operates just as it did before we left Wisconsin a week ago.

I am prepared to replace the XYZ switch, but I don't have confidence that this is the faulty part... does anyone have any insight as to what else it MIGHT be before I replace something that doesn't fix the issue? Another complicated part to this situation is that I wont be able to test the higher temperature failure for a couple more months, or unless I drive south again, which I wont do with the possibility of running into complications.