Dodge RAM 1500 1998 Owner's Manual page 1982

DR
VALVE BODY (Continued)
1-2 SHIFT CONTROL VALVE
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. 262):
• Aid in quality of the 1-2 upshift.
• Aid in the quality and timing of the 3-2 kick-
down ranges.
When the manual valve is set to the DRIVE posi-
tion 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 accumula-
tor piston by the 1-2 shift control valve. During the
1-2 upshift, this pressure is used to control the kick-
down servo apply pressure that is needed to apply
AUTOMATIC TRANSMISSION - 48RE
the kickdown and accumulator pistons. Thus, the 1-2
shift point is "cushioned" and the quality is
improved. During a WOT kickdown, kickdown pres-
sure 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, add-
ing to the spring load on the valve. The result of this
increased "modulated" throttle pressure is a firmer
WOT upshift.
Fig. 262 1-2 Shift Control Valve
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