1-2 Shift Solenoid (Auto Trans Only)

Transmission 1-2 Shift Solenoid Circuit Diagram:

Transmission Shift Solenoids:

DESCRIPTION
The 1-2 and 2-3 shift solenoids are computer controlled devices used to control fluid flow acting on the shift valves in the transmission valve body. The solenoids are normally open fluid exhaust valves used to create four different electronically controlled shifting combinations.

The shift solenoids fully determine the gear selected only when in overdrive range (D4), and have no effect on selection of park, neutral, or reverse. Both solenoids are "ON" in first gear and the computer can control 1-2, 2-3, and 3-4 shift points using the shift solenoids.

OPERATION
The solenoids get battery voltage when the ignition is turned "ON", and become energized when the PCM completes the circuit to ground. The solenoids are energized ("ON") or de-energized ("OFF") as shown when the transmission is in the ranges listed below:

RANGE 1-2 SOLENOID / 2-3 SOLENOID
______________________________
PARK "ON" / "ON"
REVERSE "ON" / "ON"
NEUTRAL "ON" / "ON"
1ST GEAR "ON" / "ON"
2ND GEAR "OFF" / "ON"
3RD GEAR "OFF" / "OFF"
4TH GEAR "ON"(with TCC applied) / "OFF"

The PCM de-energizes the 1-2 shift solenoid, allowing it to exhaust fluid pressure to initiate shift from 1st to 2nd gear. The PCM de-energizes the 2-3 shift solenoid to initiate shift from 2nd to 3rd gear. With the 2-3 shift solenoid de-energized, the PCM energizes the 1-2 shift solenoid again to initiate shift into 4th gear.