Q: Transmission shifts up and down randomly.

asked by on January 16, 2017

While driving highway speeds (60+mph) the transmission seems to 'downshift' and my RPMs jump from 2000 to 3000 which causes the engine to run extremely hard as if I am flooring the pedal. The problem fixes itself when I either slow down enough for the speed to match the RPM displacement or sometimes its possible to accelerate out of the problem. Typically, it seems like an electronic issue and doesn't cause the jeep any other 'visible' physical problems other than overclocking the engine but the last time this occured I felt a jerk as if it really did downshift. I have seen many possible solutions for a variety of problems. I would like to narrow it down to just a few.

My car has 200000 miles.
My car has an automatic transmission.

Hi There, What you are describing sounds like possibly a bad speed sensor or potentially a faulty transmission control module, which also controls the speed sensors. The transmission control module has various sensors such as vehicle speed sensors, wheel speed sensors, throttle position sensors, turbine speed sensor, and transmission fluid temperature sensors that all direct information to it in order for it to perform it’s function. Other functions controlled by the TCM are components such as a kick down switch, traction control system, and cruise control module. Any of these may also affect the way the transmission control module performs and controls the transmission and the shifting of your vehicle. A faulty transmission control module may cause also cause a delay in acceleration or erratic shifting of gears. Lastly, this may also be a result of low transmission fluid. I would suggest having a professional from Your Mechanic come to your location to properly diagnose your transmission problem.

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