Hard Shiften Yukon

I have a 97 Yukon with 140,000 miles. When the weather is very hot, and I have driven it for several miles, it will shift very, very hard. I think it may be temp related cause it only seems to do it when the weather is hot. On cool mornings or cooler days it shifts fine. I'm going to replace the cooler to see if that will help. Anyone have any other suggestions I should check? Any ideas on name brand or type of cooler?

Thanks

Yukons/chevys have a tranny problem. Check engine light will come on pulling code p1870, which is for the tranny.

If you turn your car off for a minute, it will reset and wont happen till you drive again for a while. Mosly a hard 1-2 shift.

Most places will tell you that you must replace or rebuild the tranny. Not so. All you need to do is replace the tranny valve body, and MAYBE the solenoids. That will more than likely fix the problem at a fraction of the cost.

Personally, it doesnt bother me. Been driving for 2 years with the hard shift, of course I only get it once in a while cause I dont drive so much.

Simple google seacrh will give you a plethora of details:

http://www.google.com/search?num=30&hl=en&lr=&newwindow=1&safe=off&rls=GGLD%2CGGLD%3A2005-01%2CGGLD%3Aen&q=code+p1870+Yukon+transmission

Thanks. I've read some info about Sonnax valve body kits would fix the problem also. I drive mine lots. Will have to do something or I'll be walking.