Contour Enthusiasts Group Archives Forums General Troubleshooting Transmission downshifts abruptly at highway speed

My Contour (96, 4-cyl auto) recently developed a very annoying intermittent problem: sometimes at highway speed (55-65 mph), it abruptly drops from 4th down to 3rd (with a big clunk and jerk), then promptly shifts back up (occasionally stays in 3rd for a while), then repeats. This makes the car almost undriveable at times and I'm worried about damaging an engine mount.

We have not noticed any pattern to this problem other than that it usually happens only at highway speed (e.g. no temperature or distance pattern). We also have not been able to diagnose it because both times we took it to a shop, it drove fine for them and had no codes. The car has only 52,000 miles and has been well maintained.

Any ideas? Stuck transmission valve? Worn gear? Vacuum leak? MPLS? MAS? VSS? Thanks.

i'm having same promblem now too .my mechanic is telling me its the overdrive switch that causing intermitten jerk sometimes i get the blinking lite off/on i'm taking it to him on thursday i will keep you posted

A blinking OD OFF light is the same as the Check Engine Light for your Engine, except it is for your transmission.

Take it to your DEALER.

aha- everyone told me i was crazy when I told them my OD light was blinking at me

have your tranny switch checked it might be something going bad and will cause your tranny to jerk i just had my switch replaced it was causig the same promblem but worst

Robert, do you mean the overdrive switch that you mentioned in your earlier post? Did that solve the problem? Thanks

yes its called ther selector switch it sits right on top of the tranny its probably gone bad like mines did its fine now smooth operation since i had it replaced