DTC P0747 (Transmission Control Solenoid Valve 1 Stuck On) may be setting at engine start-up when the transmission is in Park on some 2017-2019 Cruze; 2017-2020 Malibu; 2018-2020 Enclave, Envision, Regal, Equinox, Traverse, Terrain; 2018-2019 LaCrosse; 2019-2020 Blazer, XT4; and 2020 Acadia, XT5, XT6 models equipped with the 9T45 automatic transmission (RPO M3U), 9T50 automatic transmission (RPOs M3D, M3E, M3H), 9T60 automatic transmission (RPOs M3G, M3T), or 9T65 automatic transmission (RPOs M3V, M3W).
DTC P0747 may be setting due to the Body Control Module (BCM) (Fig. 9, Equinox shown) not continuing to supply ignition voltage to the Transmission Control Module (TCM) after engine shut down to allow the modules to perform a power-down self-test. If ignition voltage is not present from BCM connector X4, terminal 22, for a minimum of 15 seconds after the ignition is cycled off, the modules will not complete the power-down self-test. As a result, during engine cranking, the BCM will see data from where the self-test stopped and, typically, will see engine RPMs during cranking, which may set DTC P0747.
Fig. 9
After the engine has been running, check if ignition voltage is present at BCM connector X4, terminal 22 (Fig. 10), for a minimum of 15 seconds from the BCM after the ignition is cycled off. If the ignition voltage is not present for a minimum of 15 seconds, check all BCM power and ground connections. If no concerns are found, replace and program the BCM.
Fig. 10
– Thanks to Mark Kevnick and Tom Ellison
Amazing since the circuit description for this code says “ DTC P0746, P0747 sets only when there is a hydraulic/mechanical problem.” This is certainly helpful.