2001 Blazer Code P1870 HELP!!!!!

I have a 2001 Blazer 4x4 and had to have the radiator replaced. When the guy replaced the radiator he did not tighten up the bottom bolt and now he has to go back and fix an oil leak that somehow is associated with this bolt. To find the leak he power washed the engine and now I have more problems.
Now the tranny is slipping and yesterday the service engine light came on and we get code P1870. The guy at AutoZone did not know what the code meant so I am here for help.
I figure this is somekind of tranny code and just dont know what to do. If anyone can help me out it would be so wonderful!!

Thanks a head of time,
Sindy

P1870 is in deed a transmission code indicating a slip condition. The fact that the radiator was replaced may have something to do with it too. Idle the engine until it reaches normal operating temperature. With the vehicle on level ground, engine idling, check the transmission fluid. They may not have filled it completely when the radiator was replaced.

OK I will do that in a few minutes. Could steam cleaning the engine of caused something to malfunction? I did notice yesterday that the tranny seemed to really be slipping quite a bit.
Thanks for all of your help as I am pretty much in the dark here.

Just wanted to ask if the serpentine (sp?) belt could have anything to do with this code and the slipping. The belt is in pretty bad shape and is going to be replaced within a few days, I hope. Does the belt have anything to do with the tranny?

Getiing water into a transmission is never a good thing. Water can be in any form, whether just plain water getting in there, or in many cases, engine coolant getting into the transmission as a result of a faulty/leaky transmission cooler. A sure sign of water in a tranmission is a rusty dipstick. In this case, follow old_master's suggestion, check the level of oil in the transmission by following the procedure he outlines, you will have problems if the transmission was not filled to the proper level.

Also the serpentine belt has nothing to do with a transmission slippage code, but if its worn out, its a good idea to replace it, as it can cause other problems....

Just wanted to ask if the serpentine (sp?) belt could have anything to do with this code and the slipping. The belt is in pretty bad shape and is going to be replaced within a few days, I hope. Does the belt have anything to do with the tranny?

No the belt will not set a transmission code problem.
But engine running hot or transmission low on fluid or engine coolant in transmission fluid could cause transmission problems.
The code is a transmission slipping code.
Why was the rad replaced?
Was it a used one or new one.
As old master said check that transmission fluid.
Also I would suggest a pan drop and filter change and see what is in the bottom of the pan.
Clear code and see if it returns.
If it does.
Code 1870 is a bad code to have.
And the cause of it is usually a weak transmission.
But it should only be checked and tested by a good transmission tech that knows what they are doing. As there may be several causes of the code.

Some will say valve body and some will say converter and other things.

Here is a quote from a good transmission man by the name of {Transman} about it.

In a nutshell, the valve body does chronically wear in the 4L60E especially in the lockup PWM bore. The code lights when there is more then 100 rpm or so when locked up. Depending on mileage and fluid condition will determine the next course of action. The seal on the input shaft gets tons of heat and is the most critical seal in the trans. If there are high miles, usually what it takes to wear the vb, then the rubber seals as well as the Teflon ones are just as worn. The 1870 code is telling me there is a internal leak in this trans...someplace. The transmission is a multitude of leaks and it is engineered that way, some are good leaks because they lube planetaries and some are not so good because they make the pump work harder to make up for the leaks inside. Teflon rings leak to get enough holding power to not leak. The point here is if you have excessive or extra leaks then the PWM must cycle higher pressure and volumes to compensate making it work harder and the very forces that wear out the vb bore are increased wearing the bore quicker. In addition to that factor, with internal leaks you also have increased temperature and heat kills big time in a tranny plus it decays the additives in the fluid itself and now you are in a downhill spiral as the trans self destructs form leaks and heat and destruction of the fluid itself. Now the hard parts will start to wear at an increased speed, the pump is trying to maintain for the fluid loss(leaks), the planets will start overheating as the bushings wear out you generate more hemorrhaging and more damage.
Yes, at that point the vb is a bandaid, it may solve the problem for now but the internal wear and hardening of the seals is still there and will continue to wear. The problem I have with just throwing a vb at this problem is simply, the worn components will make the new vb work harder and cycle more than it should and the consequence of that is another prematurely worn out vb and ultimately overhaul of the trans that you should have taken care of before. The transmission is a complete and interdependent unit meaning all parts rely and interact on each other. If one part is worn out then you must deal with the unit on the whole. There are exceptions to every rule and the jeep is a good one, the accumulator plate is held down by too few screws and the plate is under enough pressure that when the screws break, the plate peels back like a lid on a dog food can. If caught soon enough then a repair of the valve body is sufficient to be a complete repair. If you have a 4L60E with 100k on it and smokey fluid and only a P1870 then you are not doing the customer a service by simply replacing the vb.
I have yet to take a trans apart that was simply coding 1870 and not found hard seals or other problems internally. Most of the time, I have not even needed to deal with the vb at all, aside from basic clean up and solenoid replacements. I have had to replace more transfer plates than valve bodies from the balls eating through. In the past 6 months, I have replace 2 valve bodies. I do not use the sonnex kit although the place I get my vb's from does.
I hope this helped you understand why I claim the 1870 code means internal problems more than just throwing a vb in my experience. {BY Transman}

I checked the fluid and there was very little so I filled it to where the dip stick said it should be for a hot engine. I drove around and the slipping is no where near as bad as it was but it still slips a bit. The service engine light is still on as bright as ever.

I put in a brand new rad because the water res was cracked on the old one. The blazer never over heated but did leak water on the oppisite side of where the rad cap is.

tomorrow I will have the tranny fulid and filter changed, see what the pan looks like and reset code. Then if the light still comes on I guess I may have to take it to a tranny shop, ones in my area love to see women come in because they think we are all idiots, and have them take a look at it. Needs a fluid change anyway but the P1870 code really bothers me as I simply can not afford to replace the tranny right now.

Thanks so much for all of the help you all have given to me. I will let you know what the tranny shops say's.