Vanden Plas (X308) V8-4.0L (AJ27) (2000)
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Shift Solenoid: Description and Operation
Hydraulic Control - Transmission Pressure Regulators and Shift Solenoids
Operation
Fluid flow within the transmission assembly is controlled by three solenoid valves and five pressure regulators.
The TCM supplies an internally switched +12V supply to each shift solenoid and pressure regulator. Hydraulic pressure from the pressure regulators
is controlled by 'pulse width modulation' (PWM) of the ground switching signal i.e. the duty cycle, the time that the pressure regulator is switched on.
Control of the solenoids is effected by switching one side to ground through the TCM.
During normal operation the TCM monitors 'Switch On' of the solenoids, regulators and the TCM output stages, but does not check output stage
'Switch Off'.
Voltage is monitored at the regulators and solenoids for continuity and shorts. For example, when a solenoid is ON the voltage on the TCM side
should be ground, when OFF the voltage should be +12.
Shift Solenoid
