(m30/m32) 4l60e / 4l65e valve body assembly complete ready to bolt on out of the box! corrects common irreversible issues with valve body wear. This problem is the number one most overlooked issue by other re-builders. One indicator of this issue is the p1870 code.
If this valve is not installed, even after a rebuild transmission can become overheated and as a result can burn up quickly do to torque converter slippage, caused by the badly worn valve body casting in the converter clutch regulator valve bore. The oem tcc valve on 4l60-e units wears the bore, creating pressure leaks that affect performance.
This regulator valve kits allow you to restore hydraulic integrity without replacing the bore. Common issues with this are overheated converters, harsh 1-2 shifts, burned 3-4 clutches, and failed lock up converter clutch.
Symptoms:

Code 894, 1870
Overheated converter
Low TCC apply pressure
3-4 Overdrive Clutch burned
1-2 / 3-2 Harsh Shifting
Low line Oil pressure
Cause:
Excess wear at TCC regulator Isolator valve bore allows regulated Torque Converter apply pressure to exhaust. Excess wear at the isolator valve bore reduces TCC apply pressure. This is a primary cause for TCC-related slip code P1870 and overheated converters.
Correction:
Recover hydraulic control and renew TCC performance by reconditioning the bore and installing TCC regulator and isolator valve kit. This sleeve is manufactured from highly wear-resistant alumium material.