My buddy has a '94 850 with only 84,000 miles on the odometer. A few days back, when he was reversing from a parking spot, the tranny started acting extremely strange. Car was in reverse, yet it didn't seem like it wanted to move (it was as if the brakes were being appplied). RPM's rose, but no car movement.

Gave it more gas, and the car suddenly/ violently jerked backwards. When put in drive, the car started to move slowly, hesitantly, again as if brakes were being applied (which they weren't).

Left the car there and walked home. This morning, we went back to car, it started right up, all was normal again. The tranny behaved properly, and we drove it back to his place.

We then decided to take it back to the mechanic (who had done something to the shift lock button the previous day, and also replaced a serpentine belt tensioner assembly), to get his opinion of the new problem.

This time I was driving the vehicle, and as I started to pull away from the curb, the same thing happened as before (car in reverse, no movement). Put it in drive, and a slow hesitant jerky crawl forward. Turned the car off for a few minutes, moved the shift lever forward/ backwards a few time, and all was well again.

Mechanic (and I) heard a slight noise coming from car when it was in low gear/ reverse). Noise disappeared as car automatically shifted into higher gear when accelerating. Mechanic thinks it's the planetary gear, the tranny is shot, $2800 repair job. I highly doubt any of the repairs he completed one day earlier have anything to do with the latest problem.

Took it to an independent tranny shop, who ran a diagnostic on the computer. Code stated that there was problem with a drive selector switch. Could a bad drive selector switch possibly be causing this problem? Auto tranny fluid was clean and at proper level.

Independent shop is also leaning towards the planetary gear (based on a test drive), but it sure would be nice if it was only a problem with the drive selector switch. Any opinions appreciated.