2001 Z71 4L60e still pops up a P1870 and harsh 1-2 shift

Irri4894

Original poster
Member
Apr 26, 2021
7
Washington DC
Hello I got a 2001 Silverado Z71 4x4 4L60e. I recently installed a new ShiftRite valve body, fluid and filter because I was getting a P1870 code and harsh 1-2/2-3 shifts after 10+ highway mile trip. Also the converter lockup showed no evidence of locking up. The rpms did not drop after cruising in 4th gear.

After the new valve body install I now have harsh 1-2 shifts only. No matter if trans is cold or warm. After a 20+ mile tripe I ran the codes and had a pending code for P1870 again. Also converter still showed no signs of locking up (no rpm drop after 4th gear.)

If the new valve body didnt fix the issue then what could the issue be?
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
The P1870 might be caused by a worn TCC clutch. So you replaced the entire valve body? Did it have a PWM elimination kit installed? If not, that might help. This thread has info and he also had the hard shifting.

Transmission fix for throwing code when using overdrive (P0894/P1870)

Some more to read:
Slight hesitation or bucking in 4th gear
4L60E valve body upgrade kit, AKA P1870 "code buster"
Code Buster shift kit installation (OffRoadTB.com)


And apparently this mod to the solenoid works without any kit:

 

Irri4894

Original poster
Member
Apr 26, 2021
7
Washington DC
The P1870 might be caused by a worn TCC clutch. So you replaced the entire valve body? Did it have a PWM elimination kit installed? If not, that might help. This thread has info and he also had the hard shifting.

Transmission fix for throwing code when using overdrive (P0894/P1870)

Some more to read:
Slight hesitation or bucking in 4th gear
4L60E valve body upgrade kit, AKA P1870 "code buster"
Code Buster shift kit installation (OffRoadTB.com)


And apparently this mod to the solenoid works without any kit:

By worn TCC clutch do you mean the torque converter itself might be worn?

and thanks for the PWM mod. Ill have to try that next time im in there.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
By worn TCC clutch do you mean the torque converter itself might be worn?
Yes. If the clutch inside is worn, no amount of pressure or PWM removal will cure that except if it's just marginal. Worth a shot with the mod.
 

Irri4894

Original poster
Member
Apr 26, 2021
7
Washington DC
Yes. If the clutch inside is worn, no amount of pressure or PWM removal will cure that except if it's just marginal. Worth a shot with the mod.
Yeah ill try the mod since ill be changing out the 1-2 accumulator pretty soon. This is the 4th damn time ill be tearing the thing apart in 1 month.

also i posted another thread question about the gauge cluster. If you could help me out with that too itd be greatly appreciated.

Again thanks for all your help!
 

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