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Code 1870

31K views 38 replies 16 participants last post by  gman 
#1 ·
Well heck, my "Service Engine Soon" light came on today and I was sure it was a P0440 code since I only had half a fuel cap. I replaced the cap and checked the code and it turned out to be 1870 trans slipping.
Didn't expect this 'cause the trans feels fine but guess not LOL
I bought a case of trans fluid and a new filter and tomorrow after work I'll use our trans fluid exchanger to clean it out. Hopefully that will at least slow the slippage a bit. Guess we'll see.
I'm just finishing a C6 rebuild using some 4R100 parts so at least I'll have room on my home work bench for the next job!

Jon
 
#2 ·
The 1870 code is normally the torque converter clutch slipping, but its usually not the convertetrs fault. There is a valve in the valve body (Called the TCC Isolater valve...I think) that controls TCC apply and it is a busy valve (meaning its always moving) so it wears out its bore in the valve body, aluminum bore-steel valve, when the bore wears out it allows fluid pressure to pass by instead of putting full pressure on the tcc valve, this causes the converter clutch not to get enough apply pressure and it slips, it only has to be a couple hundred rpm to set the code, and the only time you will notice a problem is during tcc apply, very hard to tell unless you have a tachometer, you may also notice a harsh 1-2 shift after a highway drive, this is because when the pcm senses the slipping it boosts line pressure to stop the slipping and save itself. Google P1870 and you will find tons of info on it, its very common, there's a simple fix that most tranny shops can do in a couple hours, they tear down the valve body and they have a special reamer that they use to enlarge the bore, then they replace the valve with an oversized one and your back on the road, the local shop here quoted me $150 if I brought the valve body in, if you have a ton of miles then you may want to rebuild the whole thing anyway but get the valvebody rebuilt, lots of people just tear the tranny down put in new clutches and seals and forget about or don't know how to properly inspect the valve body then the worn out TCC Isolater valve/bore allows the tcc to slip causing exccessive heat and then they burn up a fresh tranny, don't overlook this! One more thing, there are different torque converters for these transmissions so make sure you get the correct one if you rebuild the trans and replace it, they changed the clutch material inside them a couple of times over the years and they changed the computer program to compensate for the aggresiveness of the materials, there's a ton of info on the web so just do your research, good luck and let us what you do to fix it. Sorry for the long post but I had nothing better to do. Hope this was helpfull! :banana:
 
#3 ·
http://www.superiortransmission.com/Pro ... cfm?ID=196
:ty:
Thanks GMCGUY, Lots of good info! I found, as you said, all kinds of info on the web. Looks like this is the kit I want. It also modifies the TCC valve to an on-off operation rather than a constant state of slippage. A valve body drop and repair is no big deal then, followed by the flush and filter change, I should be good to go!

There was also some entertaining info out there on another forum where the site admin was advising a newbie to drill a relief hole in the TCC plug "with the valve body installed" Yikes!
 
#4 ·
I use the TransGo 4L60E-HD2 kit. It fixes the 1870 problem and beefs-up the rest of the tranny. All the shifts will be quick/precise when you are done. I've installed that kit in a couple Astros and a couple other vehicles... with great results each time.

My latest toy ['97 K1500 extented-cab Z71] had the 1870 problem. I installed the HD2 kit the week of Thanksgiving. On my test drive, the retainer ring for the servo came off, and I dribbled 5 qts of ATF around the block. :banghead: After I put the ring on correctly and re-filled the tranny, all is well - TCC locks, now and all the shifts are sweet! :banana:

Be sure to use a bottle of Lube Gard when you re-fill the tranny. That's good stuff, too :rockon:
 
#5 ·
I dropped by Transtar and picked up the transgo kit. I decided to go with the Sk-460LE kit after talking to a local trans shop owner who warned me that the HD2 kit could result in a fractured input shell.



I also picked up the pressure control valve


And the upgraded Accumulator valve.


Picked up a valve body gasket set and a tailshaft seal


And an updated Lockup valve (incase the valve body has been updated by the dealer). If it has, there should be a stamp on the valve body.




I also picked up a trans cooler.



Hopefully I'll have time this weekend to get it done. I'm getting the van smogged today after work. I've been keeping it off the freeway and out of Overdrive to keep the "Service Engine Soon" light off LOL.
Thanks GMCGUY and 97TurboAstro for all your advice!
 
#8 ·
The cost was about $300 but that includes a full gasket set and the other updated valve both of which I may not need.
Also cheaper without the cooler which was around $60.
The van passed smog today! Now I can drop the valve body and get to work!
I'll take pics along the way. Might be a few days before I get started though.
 
#10 ·
Here is an alternative that may also help, it is cut/pasted from an earlier post. If I knew how ot point to it, I would have done this:

I had a good friend that is a transmission mechanic help me with this fix. However, it is possible for the shade tree mechanic to perform to do:

We bought the parts from Transtar: http://www.transtarindustries.com/
Total cost was under $30 plus the AT filter and AT fluid. I was able to pick it up at a local distributor w/out paying shipping. Note: Since you are removing and re-installing the valve body you'll be replacing more AT fluid than when you are replacing the filter alone.

(1) Upper Valve Body gasket
(1) Lower Valve Body gasket
(1) TCC valve - Teckpak A74741Q. - May also be called fitzall by Teckpak- P1870 code fix for '95 & '00 4L60E - however, mine is a 1999 - I think the & sign (ampersand) is a misprint and should read '95 - '00, but I could be wrong. So far it has worked well for me.

There are brief directions that come w/ the teckpack, but it is basically a remove and replace of the TCC valve:

Here are 3 videos you may want to review first that cover removal and replacement of the valve body:

Removing valve body:

Note: We did not remove the electrical connector (1st instruction in the video) but did this inside the valve body

Tear down of valve body:
... re=channel

Install valve body:
... re=channel

Other than these instructions, we made sure we knew where all the bolts came out of so we could put them back in the same place, and also cleaned the throttle body real well with brake cleaner.

This fix doesn't require reaming out the valve body, and so far the transmission has shifted flawlessly. It isn't a bandaid, and is being done in transmission shops. It's up to each individual to decide which fix they want to perform for this problem.
 
#11 ·
I did the two main fixes for the 1870 code (TCC Valve and Pressure Control Valve)
The trans shifts great but the code came back. :banghead:
Thanks for the info MDCONVERT. For me at least, the last two links don't work.
I brought the van in on my day off, put it up in the air and pulled the valve body.
The fluid was dirty but there was no debris at all in the pan.

(Shallow pan, no step)

I replaced the pressure control valve and the tcc valve with the "fix" parts from Transgo.
Worked the valve back and forth in the bore to make sure it slid freely.



Added the check ball in the spring behind the torque valve and the upgraded spring behind the low valve.


Added the updated spring in front of the 1-2 accumulator valve.


Here's the location in the valve body


Installed the new spring in the 4th accumulator and a new seal on the piston.


The only thing I didn't do was install the new servo spring and drill out the valve body.
It was getting late and the van was my ride home so it had to go back together!

Also didn't add the cooler yet. There's no break in the lines so I'll have to cut into the line and flare it.
It wasn't a wast of time, the van shifts great. the 1-2 shift is firm and all the others are firmer.
 
#12 ·
Couple things, the clutch in the converter may be toast anyway as a result of the slipping. Also, from what I had read it sounded like the tcc valve wears out the bore in the valve body, the valve itself doesn't really wear because its steel and the valve body is (softer) aluminum, the fix I have seen is to use a special reamer to enlarge the bore and then install an oversized valve, much like boring a cylinder in an engine and replaceing with an oversized piston to correct cylinder wear. Did you check the bore with the old valve installed to see if you see light pass by?

Check out this video.

http://www.youtube.com/watch?v=RAKDWEI7 ... ata_player
 
#13 ·
WOW, What a great video series! Thanks GMCGUY!

I did this in a kind of down and dirty fashion and got the same results! Now that I'm familiar with this valve body, I'll take it back apart and do the light check. The transgo tcc valve is supposed to be shaped differently so that it seals against an unworn part of the VB.
I didn't do the light check but, after watching the video, I have no doubt the bore is worn.
I think I'll just get the reamer kit, a new torque converter and go back and do it right.

Thanks again and Merry Christmas everyone!
 
#14 ·
That cooler kit you had looked like it had some fittings so you can disconnect a line at the radiator and hook up there, that's what I did on my truck and it worked well. Just unscrew the top line, put the barbed fitting on the steel line and another in the radiator, then just hook your cooler hoses up to them.
 
#18 ·
chargedbird said:
Phantom,
Thanks for the info, next question, I need to drive this van one more week before i get the parts. Weill this damage anything or should I need to know anything. I am only driving 35 miles per day, for only 5 days....do you think it will be ok?

Thanks
That would depend on what type of problem you are having ......
 
#22 ·
Hi All!

Way to wake up an old post! Just wanted to say that after almost a year of driving, the trans is still perfect and there are no codes, so this repair has worked perfectly.

Thanks for all the help!
 
#24 ·
Look back to the pics at the beginning of the post. You'll see all the part #s :rockon:
 
#25 ·
chargedbird said:
Cool, Ok now I can just order a VB Kit....I know you are very intelligent with the Astro so I would like to know what VB kit would you install.

Thanks again for all the information.
I would compare the brands for price and quality , but many brands are likely to be about the same , I would examine warranty policy and contact various sources of people who have used them and find out who is happy or displeased , but concerning this project it would seem that most well regarded reputable companies would be fine , looks like some may go a little deeper than others as to how many parts are changed out , and that could be a personal choice , some kits seem moderately priced and others considerably higher , kinda depends on how much you can afford and if you think you need the extras .
 
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