Transmission code

My SES light came on today so i swung into Advanced Auto and scanned it and it read P1870, Manfacurer Control Transmission. I'm thinking what in the world does that mean. But right before the light came on the truck went through a series of hard shifts for like an hour but thens stops, i have been having the hard shift problem ever once in a blue moon. However this is the first time i ever had a light cuz of the tranny. The guy behind the counter said it's most likely a solenoid but theres really no way to tell. Anyone had this problem before or know what it may be?

P1870 is Transmission Component slipping. It can be set for any of the following:

1) A mechanical failure of the shift solenoid valves
2) A mechanical failure of the TCC solenoid valve.
3) A mechanical failure of the TCC PWM solenoid valve.
4) Internal tranny failure can also set the code.
5) An engine misfire may erroneously set the code.

Since you had some rough shifting, you probably are have a valve stick or fail.

The 4L60E is famous for this. Transgo sells a reprogramming kit for the 4L60E that addresses many of the P1870 issues. Sonnax also sells parts to repair P1870 issues.

The sonnax website is down right now but you can look at it later for P1870 fixes.

www.sonnax.com

//2000CAYukon

Ok, none of that sounds too serious or expensive. But is this something i should really be worried about? driving it today nothing was abnormal except for the light being on. Some time in the next few months i do plan to buy a shift/bulid kit and a corvette servo to wake the tranny up a lil.

I have a 97 truck and it did the same thing i checked with everybody and finally talked to a GM tranny tech that told me there was a tech bullitin on this. the valvebody and the spool are machined in two differant places. The whole valve body had to be replaced. it was around $650 .

EEWWW!!! $650!?! If i have to do that ill just let the truck sit for a month or so and just get a whole new tranny.

I was driving it today and noticed the light went off. It has been shifting like a dream all day yesturday and today. So unless it becomes a more persistant problem i'm not gonna be bothered by it. I mean it's a chevy, it'll fix itself anyway.

The hard shift problem is caused by the tranny going into gimp mode which means it boosts line preasure to get you to a tranny shop. If you go with a whole new tranny youll spend around 2500 to 3500. you can r/r the valve body yourself. or you can call your dealership and coplain and see if that gets you anywhere. It might. They offered to do mine for the cost of the valvebody.