1-2 Shift Solenoid Valve
The 1-2 shift solenoid (SS) valve is a normally open exhaust valve that is attached to the valve body. The PCM/TCM controls the solenoid by grounding the solenoid through an internal quad driver. The 1-2 SS valve is ON in FIRST and FOURTH gear. When commanded ON, the 1-2 SS valve redirects fluid to act on the 1-2 shift valve.
There are 2 PCM/TCM related diagnostic trouble codes (DTCs) associated with the 1-2 SS valve: P0751 and P0753.
The PCM/TCM monitors the 1-2 SS circuit for an open or short to ground condition. If the PCM/TCM detects an open or short to ground condition, DTC P0753 sets. If the PCM/TCM detects an incorrect gear ratio, DTC P0751 sets. When DTC P0753 or P0751 sets, the PCM/TCM commands maximum line pressure, freezes shift adapts from being updated, and inhibits 3-2 downshifts.