Hello

I have a problem with the trans in my car. This summer it lost engine braking and ses light sayed a trans slip code 1870. I droped thr trans out put a TCI rebuild kit, B&M Shift kit, B&M 2000 stall converter, and Jet power shift servo. I trans works great shifts so hard and i can't feel it slip at all. I fact it shifts so hard i leave off the gas when i and just out driving around so it don't spinn the tires. Know my problem is the SES light came back on after 50 ot 100 miles and it is still 1870 trans slip code????? Please help i don't know what is wrong.

Thanks

 

That code is 99% of the time caused by no converter lockup.
I didn't see what year your car was, but 1995 and later 4L60-E used a Pulse Width Modulated TCC apply, and was prone to failure. The #1 cause for failure is the valvebody. It wears out and the valve side loads and gets stuck, and it bleeds off critical pressure.
The TransGo kits offer a "fix" for it, but I have always opted to ream out the valvebody and install the Sonnax valve kit.

Could also be a bad TCC solenoid.

 

Thanks man

My car is a 97 30th. I also replaced the converter lockup switch. becouse me farther and i brock it when we were tacking the pump off. Also where is the bad part you are talking about??? I am not very good with auto trannys. and how would i got about fixxing it???

Thanks for all the help

 

Do a search for this code and you will find some info on it. It is very common on 97's. I get it once in a while too although my trans has never slipped or missed a shift. There is differing opinions on what to do. The tranny guys say to ream out the valve body and put the Sonnex kit in. I chose not to do anything. I put on a tranny cooler on about a year ago and that greatly reduced the accurance of the 1870 code but I still get it about once a week or so.

 

If you lose engine braking in manual 1 or 2 or Drive, then it is most likely the input sprag (broke) and/or overrun clutches (burnt) or overrun hub (broke). The transmission needs to come out for this, and while in there do some updates/improvements.

 

I already fixed the problem about on engine bracking i put a tci rebuild kit in b&m shift kit, b&m stall, jet shifting servo's and the olny problem know is that the ses light came back on and sayes 1870 tranny slip.

I don't know what you mean by "ream out the valvebody and install the Sonnax valve kit."

Also after i had the tranny rebuilt i never had it slip or miss a shif that is why i don't under stand why the ses light came back on

Thanks for all the help

 

There is a valve in the valve body whos bore supposedly wears out. Sonnex is the name of the company that makes a sleeve kit for this valve. I beleive the valve is the TCC control valve. Sonnex has info on it on their website Sonnex.com. What im saying is that on 97 cars you can get a 1870 code when there is nothing wrong with your transmission. There are guys who disagree with that statement. Why the code comes up is a question I am seeking answers to also. Your case is different because you have done internal work on your tranny. Most other times this thread comes up the tranny in question is stock.

 

Thanks man that helps out alot. Something else that code was poping up before the tranny lost enging bracking and before i did the work to the inside of the tranny. So do you think what you are saying about the valve is what is wrong with my tranny???

Thanks again

 

You don't notice anything is wrong, thats why there is the code, to TELL you something is wrong. Starting in '95, the Torque Converter lockup used a regulated apply to "cushion" the apply of the converter so that its never felt. 90% of customers don't notice when the converter locks up because of this. You don't notice there is a problem because all 4 gears work normally, however the PCM monitors TCC slip speed, so even though you don't notice the Converter not locking up, the PCM does notice it. And it doesn't even have to be 100% non functional. It has to slip at least 150 RPM for 5 seconds for the code to set.

Why does it set? The regulated apply valve in the valvebody is pulse width modulated, which means it turns on and off very quickly with varying duty cycle to create an "average" on time to change pressure to the lockup valve. Because of this, the valve is oscillating in the bore very quickly for extended periods of time. This wears out the bore and can cause the valve to side load and stick and allow apply pressure to bleed of into the exhaust port, causing no TCC apply, or very poor/random apply.
Sonnax has created a valve and a sleeve to restore OEM clearences and according to them, it should last longer than the OEM design. The only downside is you need to buy the reamer to install the service kit. So to buy the "kit" and the reamer, your out about $150, but the reamer will service 70 valvebodies, so you can always "rent" it out or re-sell it on ebay.

 

Yes, what GMTech says is the consensus on this issue. I am not motivated enough, since I dont notice anything, to do the fix. You may be.

 

Thanks guys that helps me a ton. You don't know how much that makes me mad that i put all that money into the dam tranny and then it still pops up that code. thanks for putting up with me.

If not a problem here is another question. Instead of buying that kit to ream out the bore why couldn't i just buy a new valve body or is it still cheaper to buy that kit??

Thanks

 

Thats why every tranny I get my hands into, gets a new valvebody or the Sonnax kit. Nothing is more embarrasing as a builder, then doing a tranny and the PCM spit out a Trans Slip code a month later

A "Reman" valvebody from GM will probably set you back about 300-400 bones.

 

I was woundering could you give me the part numbers for the sonnax kit and reamer please??? also would i have to remove the tranny to do this fix??? What do you think of the setup i did to my tranny is it a good reliable setup???

Thanks