P0747: How to Diagnose & Fix — Pressure Control Solenoid Stuck On

2024-2025 Silverado 1500 trucks with the 10-speed automatic (5.3L L84, 6.2L L87, 3.0L Duramax LZ0) are suffering stuck valve-body solenoids at very low mileage. Owners report a 'Service Transmission' or 'Service Transmission — Unable to Shift' message, violent hard downshifts, slipping, and complete loss of reverse — several describe rolling backwards down a slope or having to push the truck out of a parking space. The failure typically drops the truck into a default limp mode. NHTSA reports cite P0747 and P0700, and one owner had the valve body replaced only for the fault to return. The parts situation is a major secondary problem: owners document 50-plus days, and in several cases many months, waiting on a backordered valve body, with GM sometimes authorising a complete transmission. Complaint ODI numbers include 11752704, 11737852, 11702380, 11694872, 11674419, 11645507, 11640841, 11636547, 11632270, 11610139 (2024) and 11707111, 11675762, 11729153 (2025).

2024-2025 Sierra 1500 trucks with the 10-speed automatic (5.3L L84, 6.2L L87 and 3.0L Duramax LZ0) are failing at very low mileage with a stuck valve-body solenoid. Symptoms: a 'Service Transmission' or 'Service Transmission — Unable to Shift Soon' message, sudden hard/slamming shifts, slipping, complete loss of reverse (owners have had to push the truck out of parking spaces), and default limp operation limited to fifth gear and reverse. Several complaints report the failure occurring under 7,000 miles. NHTSA reports cite DTC P2818 (pressure control solenoid) and P0747/P0700. The situation is compounded by a national valve-body backorder — owners document 50-plus days and in some cases over a year waiting for the part, with GM sometimes authorizing a full transmission replacement instead. Complaint ODI numbers include 11756150, 11754176, 11748050, 11744152, 11739083, 11727368, 11721983, 11694617, 11684139, 11680422, 11680435, 11654431, 11644523, 11634982 (2024) and 11711937 (2025).

The Allison 1000 transmission paired with the Duramax diesel in 2008-2015 Sierra 3500HD trucks has a high failure rate for the Transmission Control Module (TCM). A class action suit was filed covering these years. Additional issues include input/output speed sensor failures causing no-forward/reverse conditions, and certain 2012 trucks built with incorrect thrust bearings.

Owners of 2020-2021 Cadillac CT5 and CT5-V models equipped with the GM Hydra-Matic 10L80 10-speed automatic report harsh, abrupt shifts accompanied by an illuminated check engine light. GM Preliminary Information bulletin PIP5799 documents an electrical fault in Transmission Control Solenoid Valve 7 (the line pressure solenoid) that stores DTC P2812 or P2814 in the TCM. Separately, NHTSA Safety Recall N242480630 (NHTSA 25V148) covers TCM monitoring software for a related transmission control valve wear condition that, in rare cases, can cause momentary wheel lock-up. A related Special Coverage bulletin (N242480631) extends warranty for the P0747 control-valve condition to 15 years / 150,000 miles. Note: the 2020-2021 CT5 does not include the CT5-V Blackwing (introduced for MY2022 with the 10L90), which is NOT part of this recall population.

P0700 is not a specific fault by itself — it is an umbrella/MIL-request code the ECM stores whenever the transmission control module (TCM) detects an internal transmission problem and asks the ECM to turn on the check-engine light. On the Silverado 1500 it almost always appears alongside more specific companion codes, and the underlying failure follows two dominant, well-documented patterns depending on the transmission. On trucks with the 6L80 six-speed automatic (2007-onward 5.3L and 6.2L V8 models), the internal TEHCM (Transmission Electro-Hydraulic Control Module — GM's combined valve body, solenoids, pressure switches, and TCM in a single pan-mounted unit) develops internal circuit-board/solenoid faults from heat and fluid degradation, throwing P0700 together with codes like P0796, P0777, P0842, or P0973 and dropping the truck into limp mode. On older/base trucks with the 4L60E four-speed (4.3L/4.8L), the same P0700 is typically triggered by a failed shift solenoid (P0753/P0758) or a faulty internal mode switch. Because P0700 is a stored 'passenger' code, a scan tool that can talk to the TCM (not just a basic reader) is required to pull the specific sub-code that identifies the actual failed component.