P1870 Trouble Code; "Transmission Componet Slippage"

[leo88rjd]

Hello,
I am new to the site, and look forward learning a thing or two from everyone. I do have a problem with my vehicle. Its a 2000 GMC Sonoma SLS 2.2L fuel injected truck. It has the "flex fuel" option. Anyway, this is the problem, it only has 71,000 miles on it. I took it on a trip over the Memorial Day holiday, I am driving 70MPH and suddenly it kicks itself out of overdrive, 10 minutes later the Service Engine Soon light illumunates. I pull over, check the normal stuff, transmission fluid level, etc. Everything is fine. I turned the Truck off for about 30 seconds then started back up, I then continue driving, 20 minutes later it kicks itself out of overdrive once again, 3 minutes later the check engine light comes back on. Anyway, I pulled in to a Auto Zone and asked him to read what trouble code was causing the Service Engine Soon light to illuminate, he said the trouble code was p1870-Transmission Componet Slippage. I have went to several places and all seem to say the same thing. Apparantly, the torque converter clutch (TCC) or one of the pistons within the valve body of the transmission is causing this problem.Question, has anyone had this problem and can they offer any advice in fixing this problem. I am contemplating doing it myself. I have changed turbo 350 transmissions before as well as 4 speed transmissions in older cars 71 chevelle and 68 camaro. Consequentely, I am confident I can do it myself. Is the Torque Converter Clutch (TCC) all one sealed piece that you simply take the worn (TCC) assembly out and put the new (TCC) assembly in. I know this is a lot to digress, but I am trying to save myself 650.00 bucks by doing it myself.
Any thoughts, advice, or insight would be greatly appreciated.

[ehut]

My '96 Camaro (4L60E tranny) had the P1870 code and similar symptoms last year. After some digging on the web, I found that it is often caused by a worn TCC valve. Sonnax sells a reamer and oversized valve kit to bore out the valve body by hand. Since the reamer costs $100 and will only be used once, I instead found a transmission shop that did the repair for about $270. It's been working perfect ever since. I can't guarantee that this will fix your problem, but it might steer you in the right direction. Good luck!

[leo88rjd]

Well, this is what the problem ended up being. I did not have to drop the transmission. I did have to have the valve body taken down and repaired. This is the way I--somewhat--understand it. Some transmissions have valve bodies that work on a concept known as pulse width modulation; The valve/piston inside the valve body moves back and forth "all" the time. This was my situation. What Mike at American/Foreign Transmission told me was that he was going to set the valve body up to where the valves/pistons--inside the valvebody--only moved"when they had to", not all time. He also put a shift kit in it.
I have been driving it for a couple of weeks now, and everything seems fine. I did have to pay $375.00 though. This was the cheapest price out of about 7 estimates.

[Tapdaddy49]

I have this same problem. I have a 97 GMC Suburban. If I drive around town no problem, but when I go on a trip, after driving for a while, when I come to a stop and start to take off, it slams Hard into Second gear. If I turn the Car off and back on, it doesn't shift hard anymore. I get a P1870 Code. I took it to a transmission shop and they said nothing was wrong with the transmission. He said it was something with the engine triggering it. I did some more searching on the web and found one guy that said there was a service bulletin that said something about if you run the cruise control and don't shut it off when you come to a stop that it does the slamming into second and triggers a check engine light. I have found that if I take a trip and don't use the Cruise control, I don't seem to have that problem. Don't really know how to fix it other than don't use the Cruise.