I have a 96 XJS convertible. Driving it back home from the detailer I hit a slight bump in the road and the car started downshifting on it’s own. I garaged it overnight and could not repeat the problem. My mechanic drove the car for 2 day’s and could not repeat the problem. He did notice that at 75 miles an hour the RPM’s were 2500 and that the overdrive didn’t appear to adjust to cruising. What could the problem be? Does it require a rebuild?
General transmission issues usually point to fluid, that can cause erratic shifting… When did you last replace the fluid? I change A/T fluid every 25,000 miles, and only use synthetic. Valvoline MAXlife ATF synthetic is awesome.
Another issue, since you hit a bump, could be an electrical connection. Something could easily be loose, I’d check all the wiring going to the transmission.
I doubt it needs a rebuild. That’s usually when it shifts terribly between gears, or won’t go into Drive or Reverse at all, or makes a terrible groaning noise when putting it into drive.
Thanks Greg I have my mechanic check it out.