1-2 & 2-3 Shift Solenoid Valves
The shift solenoid valves are two identical, normally open, electronic exhaust valves that control upshifts and downshifts in all forward gear ranges. See Figure and Fig 1 . These shift solenoid valves work together in a combination of ON and OFF sequences to control the positions of the 1-2 and 2-3 shift valve trains. The PCM monitors numerous inputs to determine the appropriate solenoid state combination and the transaxle gear for the vehicle operating conditions. See SHIFT SOLENOID VALVE OPERATION & GEAR RATIOS .
The PCM energizes the shift solenoids by providing a ground to the solenoid's electrical circuit. This sends a current through the coil winding of the solenoid, thereby creating a magnetic field. The magnetic field repels the plunger inside the solenoid. This seats the solenoid metering ball against the fluid inlet port. This action prevents the exhaust of fluid through the solenoid and provides an increase in fluid pressure at the end of the shift valves. This fluid pressure initiates an upshift by moving the shift valves.
Shift solenoid resistance should measure between 19-24 ohms when measured at 68°F (20°C) and between 24-31 ohms when measured at 190°F (88°C).
The shift solenoid valves should energize when the voltage is greater than 7.5 volts. The shift solenoid valves should de-energize when the voltage is less than one volt.