K 1500 Truck 4WD V8-350 5.7L (1986)
Shift Solenoid: Description and Operation
The detent solenoid is activated by an electric switch at the carburetor. When the throttle is opened sufficiently to close this switch, the solenoid in the
transmission is activated, causing a downshift at speeds below 70 mph. it lower speeds, downshifts will occur at lesser throttle openings without the use
of the electric switch.
1-2 Detent Valve
Senses regulated modulator pressure tending to hold 1-2 shift valve downshifted and provides an area for detent pressure for detent 2-1 shifts.
Shifts when oil line is exhausted at end of valve when detent solenoid is energized. This directs detent oil to the 1-2 accumulator valve, 1-2 regulator and
2-3 modulator valves, 3-2 valve and the vacuum modulator valve.
Detent Regulator Valve
When the detent valve shifts, the detent regulator is free to allow drive oil to enter the detent passage and thus becomes regulated at 70 psi.
Detent pressure will also flow into the mod lator passage which flows to the shift valves. Low gear oil moves the detent regulator open to drive oil,
allowing drive oil to enter modulator and detent passages.