Circuit Description
WARNING: This page is about a different car, the 2003 Buick Regal and 2003 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
The 2-3 shift solenoid valve is supplied with fused ignition voltage. The ground path is controlled by the PCM. When the PCM commands the solenoid OFF, a ground path is not provided and the filtered line pressure that is fed to the solenoid is exhausted. When the PCM commands the solenoid ON, a ground path is provided and the exhaust port is blocked, stopping the exhaust of line pressure.
The PCM identifies a 2-3 shift solenoid valve performance condition by monitoring the commanded gear versus the gear ratio.
If the PCM detects a 4th gear ratio when 1st gear is commanded and a 3rd gear ratio when 2nd gear is commanded, then DTC P0756 sets. DTC P0756 is a type "A" DTC.