P0747 on GMC: How to Diagnose & Fix
Pressure Control Solenoid Stuck On
2 GMC models · 2 documented issues · 2 critical · $500-$6,500 repair
P0747 on GMC by model: symptoms, diagnosis and fix
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.
Common Symptoms
- "Service Transmission" or "Unable to Shift Soon" message
- Sudden hard or slamming shifts
- Transmission slipping
- Complete loss of reverse
- Limp mode limited to fifth gear and reverse
How to Fix
GM issued TSB #25-NA-255 (Sept 22, 2025) directing technicians to REPAIR rather than replace the valve body on select 2021-2024 Silverado/Sierra 1500 (the published summary lists the LM2/LZ0 3.0L Duramax) and full-size SUVs with the 10-speed when P0747 is set; eligibility is confirmed by VIN, so ask the dealer whether it applies to your truck. The repair installs a new steel Feed Limit Low Valve, a higher-tension Feed Limit Valve Spring, and a new valve body spacer plate with gasket; it requires at least 7,000 miles on the vehicle and must not be used if there is significant clutch debris in the pan. No solenoid characterization programming is needed afterward. Ask the dealer specifically for the 25-NA-255 repair kit rather than accepting a backordered complete valve body. Repairs are covered under the 5yr/60k powertrain warranty for these model years. If clutch material is present, a transmission replacement is the correct call.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (4)
- GM Issues New Valve-Body Repair for P0747 on 10-Speed (10L80/10L90) — TSB 25-NA-255article
- GM Technical Service Bulletin 24-NA-181: No Reverse, Will Not Shift Past 3rd Gear, MIL Illuminated - DTC P2732 Set (Nov 2024)tsb
- CarComplaints: 2024 GMC Sierra 1500 automatic transmission complaintsowner-report
- Ratchet+Wrench: General Motors Trucks, SUVs Facing National Backorder on Transmission Valve Bodiesnews
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).
Common Symptoms
- Intermittent no forward or reverse movement
- Flashing PRNDL display
- Range Shift Inhibited message
- Harsh or delayed shifts
- Transmission noise or whine
- Check engine light with transmission codes
How to Fix
Scan for transmission and U-codes and check TCM connectors and input/output speed sensor wiring before replacing the TCM. For 2012 trucks, ask a dealer whether GM Customer Satisfaction Program 14043 (thrust bearing replacement) was completed; the free repair window ended March 31, 2016.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
Sources for this issue (2)
P0747 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0747 mean on a GMC?
P0747 stands for "Pressure Control Solenoid Stuck On." This transmission code means the pressure control solenoid 'A' is stuck in the on (or fully applied) position, or its circuit behaves as if permanently energized. This solenoid regulates hydraulic line pressure that controls clutches and shift feel inside the automatic transmission. When it stays on, line pressure can't be modulated properly, leading to harsh shifts, slipping, overheating, or the transmission being stuck in a gear or limp mode. It points to the solenoid, its wiring, or a hydraulic/contamination problem in the valve body. On GMC it is documented across 2 models: Sierra 1500, Sierra 3500HD.
What are the most common causes of P0747?
The most common causes of P0747 are: Stuck or failed pressure control solenoid, Dirty or contaminated transmission fluid blocking the valve, Debris stuck in the valve body bore, Shorted or chafed solenoid wiring, Corroded or loose solenoid connector, Low or degraded transmission fluid, Faulty transmission control module (less common). The specific cause varies by vehicle.
How much does it cost to fix P0747 on a GMC?
Published repair estimates on GMC range from $500 to $6,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.