99 tahoe, 4l60E, P1870 code

Jeff B

Jeff B

Thanos was right
Joined
Dec 23, 2006
Location
Lincolnton N.C.
drove out past Rockingham today. During the trip, tranny started shifting rough and threw this code.

Reading on the interwebs, looks like I need a new TCC regulator or an entire new valve body.

Anybody on here done this? Does it take specialty tools?
 
there is a mod that does not require replacing the TCC reg.. im not exactly sure what it is, but my local trans shop does. i think it involves staking the TCC PWM valve fully open, but don't hold me to it. i should have looked closely and photgraphed the VB they did for me last time... now if its already staked, you have other issues.
 
I found a video on replacing the TCC PWM solenoid. I'll try that first when I return from Montana.
 
a_kelley said:
It's not the pwm solenoid, but the pwm valve... I'll see what I can dig up to help you out.. I've got a VB here I can show you on at least.
Click to expand...

Thank you
 
the video I watched stated the solenoid would cause the same code. Was 12$ on ebay so I figured worth a shot.
 
back from vacation late last night. Up this morning to perform the mod of staking the PMW valve. Also replaced the TCC solenoid. New fluid and a quart of lucas tranny stuff and viola! no more hard shifts and no more codes. Running 80mph I noticed the rpms are about 200 less then before. So this should be a bit of a gas saver too..

Link to specific mod that fixed the issue. 97 4L60E bolt directly into a 95 car? - LS1TECH - Camaro and Firebird Forum Discussion

Thanks @a_kelley
 
I'm happy that fixed it for you. I'll have to bookmark that myself as I knew there was a fix for p1870 and involved staking a valve but didn't know the exact procedure, as the last VB I had done cost me/customer $100 just on the VB mod, with it removed. And he wouldn't tell me what was involved but was pretty certain it involved the tcc pwm valve as he looked at it and told the other tech "see this one hasn't been done yet. (And service manual mentioned this tcc pwm valve and solenoid)

The cause of the code p1870 is the valve not properly shifting in the bore and binding according to pressure supplied by the tcc pwm solenoid hydraulic circuit. So, staking the valve fully in remediates that problem by applying full line pressure when the tcc lockup solenoid seals. Gm uses the pwm solenoid only to ease into or out of lock up. So the modification doesn't really affect that all that much as earlier 4l60e's only had lock up on/off. Yes the kit and reamer would fix it as well, but not near as cheaply or as permanently, eventually the new oversize valve would begin binding in the reconditioned bore and cause the same symptoms again, though probably after a good few miles.
 
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