Circuit Description

WARNING: This page is about a different car, the 2005 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.

The 1-2 shift solenoid valve is located in the control valve body of the transmission. The transmission control module (TCM) selects the required gear by turning the appropriate solenoid ON or OFF, enabling the transmission to shift. Refer to Shift Solenoid Valve State and Gear Ratio .

The TCM provides voltage to the solenoid through high side driver 2 (HSD2). The TCM uses a second driver to control the solenoid ground circuit. The controlled ground driver reports feedback voltage to the TCM. When the TCM commands the 1-2 shift solenoid valve ON, the voltage of the control circuit should be approximately 0 volts. When the TCM commands the 1-2 shift solenoid valve OFF, the voltage of the control circuit should be approximately system voltage.

When the TCM detects a continuous short to voltage in the 1-2 shift solenoid valve circuit, then DTC P0974 sets. DTC P0974 is a type B DTC.