November 14, 2016
Vehicles with 4R70W and AODE transmissions often have erratic line pressure, poor line rise and/or throttle-sensitive buzz. This can result in harsh or soft shifts and band/clutch failure as well as other driveability concerns. Worn pressure regulator valve spools allowing pressure escape are a common problem in these units. Installing Sonnax main pressure regulator valve 76948-01 restores normal line pressure operation in all ranges.
If bore is excessively worn, install Sonnax oversized pressure regulator and boost valve kit 76948-16K.
'91–'95 PR valve and '96-later PR valve designs are not interchangeable. For '96-later PR valve, see 76948-09.
Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.