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

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. At least 14 NHTSA complaints for the 2024 model year describe this failure, for example ODI numbers 11756150 and 11754176.

The Allison 1000 transmission paired with the Duramax diesel in Sierra 3500HD trucks has a high failure rate for the Transmission Control Module (TCM). GM issued technician information (PIP4560 series) on Allison TCM parts restrictions. Additional issues include input/output speed sensor failures causing no-forward/reverse conditions, and certain 2012 trucks built with incorrect thrust bearings (GM Customer Satisfaction Program 14043).

Historical service update N242446290 identified certain 2024 XT6 inventory vehicles with out-of-specification internal transmission retaining rings. Dealers had to repair eligible inventory before delivery; the update expired July 31, 2025. This does not prove a sold vehicle missed the repair or exclude later diagnosis. Separately, PIP5974A describes possible snap-ring trouble on 2024 XT6 transmissions M3G/M3W built October 1, 2023–April 22, 2024, with P0746/P0747 and possible slipping or no drive.

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 (many 5.3L and 6.2L V8 trucks, plus 2014-onward 4.3L V6 trucks; 2015-onward 6.2L trucks use the 8L90 eight-speed instead), 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 (2007-2013 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.

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.