RAM 2500 Truck 4WD L6-5.9L DSL Turbo VIN 7 (2001)
When governor pressure builds to a point where it can overcome the combined force of the spring and throttle pressure on the other side of the valve,
the valve will begin to move over to the right. As the valve moves to the right, the middle land of the valve will close off the circuit supplying the
throttle pressure to the right side of the valve. When the throttle pressure is closed off, the valve will move even farther to the right, allowing line
pressure to enter another circuit and energize the front servo, applying the front band (Fig. 251).
The governor plug serves a dual purpose:
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It allows the shift valves to move either left or right, allowing both upshifts and downshifts.
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When in a manual selection position, it will be hydraulically~"blocked" into position so no upshift can occur.
The physical blocking of the upshift while in the manual "1" position is accomplished by the directing of line pressure between both lands of the
governor plug. The line pressure reacts against the larger land of the plug, pushing the plug back against the end plate overcoming governor pressure.
With the combination of the line pressure and spring pressure, the valve cannot move, preventing any upshift.
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. 252):
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Aid in quality of the 1-2 upshift.
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Aid in the quality and timing of the 3-2 kickdown ranges.
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.
