Chrysler Repair: my transmisson pops into overdrive, chrysler town and country, electronic control unit

Question
hi i own a 1998 chrysler town and country w/ 98000 miles on it it shifts smooth until its suppost to go into overdrive then it pops into gear, any idea on what it could?

Answer
Hi Julie,
I don't have experience with that specific behavior but it may indicate that the clutch for the overdrive gear is wearing out. There are causes of harsh upshifting that are related to the hydraulic aspects of the transmission but when it seems to just affect one specific gear or shift it makes me suspect that the clutch for that specific gear is awry. But there is one diagnostic approach that you could seek: a readout of the memory of the electronic control unit of the transmission. When the controller observes a malfunction it has the ability to codify the observation as a fault code, a two digit number, which then focusses on the specific possible reasons for the malfunction. A Chrysler dealer or a quality transmission shop should have a code reader that plugs into a port under the dash and can give you the fault code(s) if any. The important distinction is to ascertain if the behavior can be repaired without removing and dismantling the transmission which is a major cost (typically $1,500). If it were due to an hydraulic pressure or electrical malfunction then the repair would be much less expensive.
So I would suggest getting a readout, ask for the specific number of the code, what might be the repairs that would eliminate the behavior and the code, and how much it would cost. Then if you want to compare what they say to what the manual says, write back and tell me the story and we'll compare it to the Chrysler shop manual.
It may be that an adjustment of the gear selector linkage, or changing the fluid in the trans, or the filter, or changing the internal pump would solve it without having to do a removal and rebuild. So that is why spending some money on diagnosis is well-advised. These are very complex units but you want to take your time before jumping to any conclusions about what to do when they malfunction. Too often, I believe, the pat answer of a 'rebuild' is sold to an unwitting owner. You might also ask whether the cost of the readout (should be less than $50) might be applied to the cost of the repair bill if you decide to have the shop do the work.
Roland