ChevyZ76

Got this code today while driving normal. Though it was acting weird before the tq converter was part in. Be going 50 and stomp it and it feels like a turbo car spooling up, then the car takes off. But it seems fine if I leave from a stop. Never got the light before. Is there a normal fox for this? If not and I have to buy that it...would it be better to completely rebuild the trans? Thanks guys

coryforsenate

iTrader: (1)

Assuming you have a 4l60e,

There are two easy fixes to a code 1870, both involving the TCC regulator bore.

The simplest solution is to delete the isolator valve. Both Transgo and Sonnax make kits that include pieces addressing code 1870. Some rebuild kits will include a fix also. This style of solution makes the function into on/off instead of PWM.

The more complicated solution involves reaming the TCC regulator bore and installing a new, "updated" TCC valve setup. A local transmission shop may have the reamer required for this and will charge a small fee (mine charged like $15 to ream my valve body), otherwise buying the reamer yourself is crazy expensive. Depending on your opinion regarding PWM, this is "proper" fix as deleting the isolator valve gets rid of PWM. Reaming the bore keeps PWM. I've never heard anybody on here complain about losing PWM though. Sonnax makes this kit.

Either type of kit should fix your code 1870.

The Transgo kit covers just about every year 4l60e. Sonnax is year specific.


Let one of the more experienced guys comment too. I've only rebuilt my own 4l60e once.

coryforsenate

iTrader: (1)

And here's a fun picture. The TCC regulator bore is on the upper left. The valve design varies by year.

coryforsenate

iTrader: (1)

And a fun video explaining the code 1870 and the two styles of fixes. Skip[ to 3:50 for the part about code 1870.

mrvedit

Very good and complete info Cory.
P1870 occurs when the PCM detects slippage when the converter lockup clutch is engaged.
While the culprit often is a worn/leaking TCC valve (Converter Clutch Regulator in the above picture), it can also be a worn out converter lockup clutch. If a P1870 code due to a worn TCC valve is ignored for too long, it may ruin the converter too.

Stardust

Hey guys, just got this on my 96. Looks like I'll be looking for that Sonnax kit.

coryforsenate

iTrader: (1)

Same year as mine. I'll post the kit ID's I got

Contains the on/off style PWM solution. There's a bunch of other stuff in this kit for different parts of the transmission. I didn't use the P1870 fix part of this kit in mine.
http://www.sonnax.com/parts/2928

Contains the style that retains PWM function, requires reaming. I got this in addition to the Performance Pack. I wanted to keep PWM. This is just the P1870 fix, nothing else
http://www.sonnax.com/parts/2457




P.S. Sonnax, to my knowledge, does not sell a on/off style PWM solution by itself. Most everything in the Sonnax Performance Pack can be done without dropping the transmission. But if you want the on/off style PWM solution for a lot less money (Sonnax ~$150), Transgo makes a kit for the on/off style that's much, much cheaper (around $40-45). It has the P1870 fix and a few springs.

Stardust

Thanks!

mrvedit

Perhaps better and cheaper than the Transgo TCC valve is the Fitzall TCC on/off valve which includes o-rings to seal a worn bore. Note that one model is for 96-99
and one is for '00 and later:

http://www.teckpak.com/spgm.cfm?id=A74741Q for '96 to '99
http://www.teckpak.com/spgm.cfm?id=A74741QA for '00 to '02 and some later PCMs

They cost around $15 or $20 with shipping.

Stardust

That is great. I just happened to come across that same thing awhile ago and was going to come back on here to ask if anybody had seen it.

Do you see any downside in installing that part? Looks like the spring is left out? Seems like the obvious choice to me.