1-2 Shift Control Valve

WARNING: This page is about a different car, the 2004 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.

It contains a valve with four lands and a spring. It is used as both a "relay" and "balanced" valve.

The valve has two specific operations (Fig 1):

Aid in quality of the 1-2 upshift.
Aid in the quality and timing of the 3-2 kickdown ranges.

Fig 1: 1-2 SHIFT Control Valve Diagram

Courtesy of DAIMLERCHRYSLER CORP.

When the manual valve is set to the DRIVE position and the transmission is in the first or second gear range, 1-2 SHIFT control or "modulated throttle pressure" is supplied to the middle of the accumulator piston by the 1-2 SHIFT control valve. During the 1-2 upshift, this pressure is used to control the kickdown servo apply pressure that is needed to apply the kickdown and accumulator pistons. Thus, the 1-2 SHIFT point is "cushioned" and the quality is improved. During a WOT kickdown, kickdown pressure is applied between the kickdown valve and the 1-2 SHIFT control valve. This additional pressure is directed to the 1-2 SHIFT control's spring cavity, adding to the spring load on the valve. The result of this increased "modulated" throttle pressure is a firmer WOT upshift.