As a result of this post I will no doubt again be accused making an attack, but so be it. Incorrect information is not in the interests of members and requires correction. This particularly applies in respect of the arduous work covered by this thread.
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First and Reverse are both selected by the Shift lever operating the Manual valve, the No. 1 and No. 2 shift solenoids don’t really play a part in First or Reverse, they are electrically turned on, but just bleed off pressure.
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Solenoid valves 1, 2, & 3 are normally open devices and close and shut off fluid when energised (electrically turned on). In this state they do not bleed off pressure and close the bleed so that pressure is applied.
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The shift solenoids 1,2 then turned off in turn to control the selection of 2,3,4.
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These normally open solenoid valves are turned ON in order stop pressure bleed off and as a result then provide control pressure in respect of the selection of ratios 2, 3, & 4.
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The C solenoid operates the AWD. For the Transfer system, 5% is fully applied clutch, 95% is a free clutch. For the VTD AWD 5% is free clutch, 95% is a locked clutch. The B solenoid operates the converter lock-up clutch, it is not varied as much as A or C solenoids, it is just turned on or off, but the turned on, is modulated, to reduce shock.
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Solenoid valves A, B, & C, in the case of transmissions incorporating a centre clutch, are all normally closed devices. Solenoid valve C is a normally open device in the case of transmissions incorporating a centre differential.
Thus in both systems the respective C Solenoid valve is near fully energised for virtual lock up of front rear, without requiring a different configuration of electrical or hydraulic systems. Both C valves bleed off fluid as a means of control.
Cheers, Trevor.