2000 GLS Trans problem (4th gear shift problem)

I have recently noticed that my sonata has a stumble in the shift to
4th gear. If I accelerate slowly it isn’t that notceable. However,
if I accelerate at a good clip that last shift (its in drive) has a
hesitation (or stumbles as I feel it) and actually the rpms jump up
for a second before it shifts. I checked the fluid level and its
fine. I had the trans fluid changed <20k miles ago. I does have a
brownish color which seem abnormal as I though all trans fluid was
pink. It has 93k miles on it and the trans fluid have was changed at
36k and 76k. Should I just change the fluid first before I take it in
to the dealer or don’t bother as they may need to evaluate the
condition of the trans fluid? I had the speed sensor changed at about
50k becasue it was defective, didn’t know if that could be the problem
again.

 

Most likely, it's an internal problem that'll require transmission
replacement.

Technical service bulletin 03-40-015 gives details on diagnosing a 2-3
shift flare, but the things we're discussing here could cause this to
occur on nearly any shift.

The TSB indicates that the fluid temperature sensor should be checked and
that the adaptive values should be relearned prior to condemning the
transmission. You can see the TSB (and a host of other useful
information) at www.hmaservice.com. You'll need to register for a free
account, and the site requires Internet Explorer.