The automatic transmission in my 2007 Jeep Grand Cherokee started acting up around 75,000 miles into owning it. Now I would understand if it started shifting rougher or some other normal transmission problem, but this transmission will downshift at highway speed, making the whole thing slow down. It will refuse to shift out of first gear. I turn it off and back on again and that fixes it sometimes. I'm guessing it’s a computer issue, my laptop does the same thing. Expected better out of a Jeep! How can I diagnose this problem?
Sounds like you may have a problem with corrosion in the transmission control module, shift module, or in some of the engine sensors.
Reading the engine codes would lead to a more specific diagnosis, but checking for corrosion on any of the electrical connections within the transmission and cleaning out connectors may resolve the issue.
I suggest engaging a certified mechanic, such as one from YourMechanic, to scan your computer system and check specific codes for a thorough diagnosis and repair.
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