I have a 01 caravan.It is a v-6 4wd with tow package .It has 200k. It will not move. Can anyone summarize why these trans fail so often. What steps can an owner do to make them last.

 

I wouldn't call a failure at 16 years and 200K miles "real often". Especially on an AWD that tows.
However, when was the fluid and filter last changed, and what is the level now? Color of the fluid?

 

1. Lack of Proper maintenance. The severe service schedule should be followed. These transmissions have a very small fluid capacity, which means they get dirty fast.
2. Heat. Factory coolers were insufficient, leading to failure.
3. Wrong fluid. ATF+4 is the only fluid that can go in the A604 trans, anything else will cause failure.
4. Electronics. If a sensor fails or the solenoid pack gets clogged it will cause a lot off issues.
5. Abuse. Heavy towing, hard driving, etc will lead to an early death.
6. Diff pin failure.
7. Misdiagnosis by shops.

Change the fluid/filter every 30k.
Install an external transmission cooler.
Install an inline filter.
Make sure to always use ATF+4 only.
Find a happy place in your driving style, abuse it you will have issues, drive it like you're 80 you will have issues.
The diff pin can be helped by installing a diff pin keeper (aka diff pin bracket) which will hold it in place in the event the shear pin gives out.
Never trust the trans shop. Assume they are all ignorant to the A604 trans (because 90% of them are).

I wouldn't be scoffing at 200k on a 16yo minivan. Especially on an AWD model that has likely seen towing use. That's better than a lot of vehicles can ever hope to see.

Have you checked your fluid level? Being over 1/2qt low will cause them to "not move" as they can't get proper fluid pressures to do their job.