After a transmission fluid change the explorer would only go into reverse...why
The fluid level could be too low. New fluid replenishes the detergents and that could cause lots of stuff to become entrained and do two things: the contaminants newly circulating in the fluid travel to the filter and plug it up (especially if the filter was not changed and thus already might be partially plugged) and second, the contaminants get in the transmission valve body and cause valves to stick, particularly the manual valve. It is also possible for the failure to shift to be a coincidence and the actual failure lies elsewhere in external controls. The cause can be inferred by external pressure gauge testing and if you desire a diagnostic simply request a failure to shift diagnostic.
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