well my girlfriend's car has been getting a p1870 code during the warmer months and after longer trips. i did some sluething and found this: http://www.my3cents.com/showReview.cgi?id=12520 basicly what i understand is that it is an issue inside the valve body, and the whole valve body needs to be replaced. now there are no other issues other than the harsh shifts once its good and hot. i haven't been able to locate a replacement valve body, links? i was also thinking of adding an auxiliary trans cooler, as it would be cheaper to replace as well as a lot easier to do. according to the tsb, it really only occurs when the trans temp is over 200. from what ive learned in school, the cooler the trans is kept, the longer is lasts. and since the harsh shift and pending code have only occured on longer trips when the ambient temperature is over 50 degrees, i figured an add on cooler wont hurt.

i also noticed that her tcc lock up getting on the highway is a little late. i thought it may have been just her throttle input, but that is also covered in the tsb

 

go about half way down the page, u should find a couple things on the 1870 fix.
http://www.transmissioncenter.net/4l...rmance%20Parts

 

i found a shop that will do it for $100. im going to see if they can do all the required updates, they knew immediatly what was needed when i told them the year, make, and code