Wear at the low pressure control valve allows 1-2-3 regulated braking fluid to exhaust.
Install the Sonnax oversized valve and end plug kit into a refurbished bore to restore correct hydraulic clearances and prevent future wear.
The low pressure control valve applies in 1st, 2nd or 3rd gear coast conditions, when engine braking is needed. Depending on the gear and solenoid states, 1-2-3 regulated fluid pressure is routed through this valve to provide engine braking through a controlled apply of the low/reverse clutch, 2nd coast clutch or O.D. clutch. If the bore has excessive wear, this regulated oil pressure is open to exhaust, resulting in 3-2-1 bumps on coast downshifts, no engine braking, and/or clutch failure. The Sonnax low pressure control valve kit 55211-17K easily can be installed into are furbished bore, and incorporates design upgrades to prevent future wear concerns.
Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.
November 24, 2015
Topics: Vacuum Test Guides Vacuum Testing Transmission GM 5L50-E Transmission 5L40-E TransmissionRead Now
September 30, 2005
Topics: Diagnostics And Theory TransmissionRead Now
Contact a Sonnax Parts Distributor.
A vacuum test at either port indicated fails to hold 18" of vacuum or higher, or if visual wear is detected at the inboard overlap valve bores.