P0747 on 2020-2024 Cadillac XT6: Pressure Control Solenoid 'A' Stuck On Causes and Fixes

What's Unique About the 2020-2024 Cadillac XT6

The Cadillac XT6 uses a GM 9-speed automatic transmission (RPO M3G/M3W, model 9T65). For this specific transmission family, code P0747 is often a symptom of a deeper mechanical problem rather than a simple solenoid failure. General Motors has issued multiple Technical Service Bulletins (TSBs) acknowledging that internal component failures, such as out-of-round snap rings, can cause this code to appear. TSB PIP5974A specifically identifies 🎬 Watch: Expert explanation of the XT6 snap ring failure a batch of transmissions built between October 1, 2023, and April 22, 2024, as having defective snap rings that can pop out of their groove, leading to a no-drive condition. These failures can lead to catastrophic transmission damage if not addressed correctly, making an accurate diagnosis critical.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Vehicle will not move when in Drive or Reverse
• Extremely harsh or violent gear shifts, sometimes described as 'slamming' into gear
• Check Engine Light or Transmission Warning Light is on
• Delayed engagement when shifting from Park to Drive
• Transmission gets stuck in one gear (limp mode)
• Slipping during acceleration
• Grinding or humming noises from the transmission

Most Likely Causes

1. Internal Mechanical Failure (Out-of-Round or Broken Snap Ring) 🔴 High Probability Multiple manufacturer TSBs confirm this is a known weakness in the 9T65 transmission. TSB #PIP5974A directly links out-of-round 1-2-3-4-5-6 clutch snap rings to code P0747, especially in transmissions built between Julian dates 23-274 and 24-113 (Oct 2023 - Apr 2024).
   How to confirm: Check the transmission's Julian build date. If it falls within the range specified in TSB PIP5974A, this is the most likely cause. Otherwise, confirmation requires a complete transmission teardown and inspection of internal components. Metal debris in the transmission fluid is a strong indicator.
   Typical fix: The transmission must be removed and disassembled. Per TSB PIP5974A, the repair requires replacing the entire 1-2-3-4-5-6 clutch pack assembly, including the piston housing, piston, seals, return spring, plates, and retaining rings. The TSB explicitly states *not* to replace the valve body or solenoids for this specific failure.
   Est. part cost: $200-$900 for the full clutch pack component list.
2. Faulty Pressure Control Solenoid 'A' or Valve Body Assembly 🟡 Medium Probability → Shop Transmission Valve Body The solenoid itself can fail electrically or mechanically. More commonly, the solenoid regulator valve in the valve body bore can stick due to wear or contamination. Often, metal debris from another internal failure (like a snap ring) contaminates the valve body and causes the solenoid or valve to stick.
   How to confirm: A technician can use a bi-directional scan tool to command the solenoid on and off while monitoring pressure data. Physical inspection for debris is necessary if the solenoid fails the test. A key diagnostic step is to differentiate if the code sets during driving (hydraulic/mechanical) or only at startup (electrical).
   Typical fix: Replacement of the individual solenoid or the entire valve body assembly, which contains all the solenoids. This is followed by a fluid flush and transmission relearn procedure.
   Est. part cost: $300-$600
3. Low or Contaminated Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly
   How to confirm: Check the transmission fluid level and condition according to the manufacturer's procedure. The fluid should be at the correct level, red or dark brown, and free of excessive metallic debris or a burnt smell.
   Typical fix: Perform a transmission fluid and filter change. If the fluid is heavily contaminated with metal, it indicates a more severe internal problem (like the snap ring failure) that must be addressed.
   Est. part cost: $150-$300

Rare But Worth Checking

• Body Control Module (BCM) Electrical Fault: → Shop Body Control Module TSB #PIP5697B and related articles in Gears Magazine describe a rare scenario where P0747 sets during engine cranking with no actual transmission fault. The T87A TCM performs a solenoid self-test after key-off, which requires power from the BCM for at least 15 seconds. If the BCM or its wiring fails to provide this voltage, the test fails, and a false P0747 is logged on the next startup.
• Faulty Transmission Control Module (TCM): → Shop Transmission Assembly A failure in the TCM's internal driver circuit can cause it to continuously command the solenoid on, mimicking a stuck solenoid. This is less common than mechanical failures and should be suspected if all wiring and components test good.

Diagnosis Steps

1. Verify the code with a professional OBD-II scanner that can read transmission-specific data.
2. Check the transmission build date (Julian date) against TSB #PIP5974A. If it falls between 23-274 and 24-113, suspect the internal snap ring failure.
3. Check the transmission fluid level and condition. Dark, burnt, or metallic fluid points to a serious internal problem.
4. Use a bi-directional scan tool to monitor live data from the TCM, including commanded vs. actual line pressure and solenoid states. Note *when* the code sets (on startup vs. during driving).
5. If the code only sets on startup, investigate the BCM power supply to the TCM as per TSB #PIP5697B. Check for voltage at the specified TCM pin for at least 15 seconds after key-off.
6. Perform an active test on Pressure Control Solenoid 'A', commanding it on and off to check for a response.
7. Inspect the transmission wiring harness and connectors for damage or corrosion.
8. If significant metal debris is found in the pan or fluid, a full transmission teardown is required to inspect for failed snap rings or other mechanical damage, as per TSB #PIP5974A.

Parts You'll Likely Need

• 1-2-3-4-5-6 Clutch Pack Rebuild Components (OEM #Various (Kit or individual parts)) — This is the complete list of parts mandated by TSB PIP5974A for the snap ring failure repair. It includes the piston housing, piston, seals, spring, wave plate, clutch plates, backing plate, and retaining rings.
  Trusted brands: ACDelco / GM Genuine Parts
  OEM price range: $200-$900
  Aftermarket price range: N/A (OEM Recommended)
• Transmission Valve Body Assembly (OEM #24043133) — Often replaced if contaminated by metal debris from a snap ring failure or if the solenoids are confirmed to be faulty. This part number is applicable to a wide range of GM 9TXX transmissions. Note: GM explicitly states NOT to replace this for the specific snap ring TSB issue.
  Trusted brands: ACDelco
  OEM price range: $450-$600
  Aftermarket price range: $350-$500
• Pressure Control Solenoid (OEM #24248893) — This is the component directly named by the code. It may be replaced if it has failed electrically or is stuck, but it's often a symptom of a larger issue. Technicians note the solenoids themselves are robust and rarely the root cause.
  Trusted brands: ACDelco
  OEM price range: $50-$80
  Aftermarket price range: $30-$60

Related Codes That Often Appear With This One

• P0746 — P0746 ('Pressure Control Solenoid 'A' Performance/Stuck Off') is the companion code to P0747. Both are often caused by the same underlying mechanical issues, such as faulty snap rings, as noted in TSB #PIP5974A.

Technical Service Bulletins (TSBs) & Recalls

• PIP5974E: This Preliminary information communicates possible transmission 1-2-3-4-5-6 snap rings out of round causing code p0746 or p0747.
• PIE0720A: ...gathers further information from technicians in regards to Vehicle Will Not Move When in Drive, Neutral and/or Reverse and DTCs P0746, P0747 Set.
• PIP5697B: This Preliminary information communicates a possible BCM concern if DTC P0747 sets during engine cranking when the transmission is in park.
• PIE0720: ...perform the check list provided and contact the engineer listed in regards to Vehicle Will Not Move When in Drive, Neutral and/or Reverse and DTCs P0746, P0747 Set.

Platform-Specific Known Issues

• TSB #PIP5974A: Specifically calls out that out-of-round 1-2-3-4-5-6 snap rings can cause code P0747. It provides a specific manufacturing date range (Oct 2023 - Apr 2024) and a detailed list of parts to replace, warning technicians *not* to replace the valve body for this issue.
• TSB #PIE0720A & #PIE0720: GM has actively gathered field data on vehicles with P0747 that result in a "Vehicle Will Not Move" condition, highlighting the severity of this fault and the company's focus on understanding the root cause.
• TSB #PIP5697B: Documents a rare electrical issue where the Body Control Module (BCM) can cause a false P0747 to be set during engine cranking because the TCM did not receive power for its post-shutdown self-test.

Mechanic-Grade Diagnostic Values

• Transmission Fluid Temperature (TFT) for Fluid Level Check — expected: 85–95°C (185–203°F). Failure: Checking the fluid level outside this temperature range will result in an inaccurate reading.
• Transmission Line Pressure at Idle — expected: Greater than 345 kPa (50 psi). Failure: Pressure below this threshold indicates a potential pump, leak, or fluid issue.
• Pressure Control Solenoid Resistance (Typical for GM PWM solenoids) — expected: Around 5 ohms. Failure: Very high or infinite resistance indicates an open coil; very low or zero resistance indicates a short.
• BCM Voltage Supply to TCM after Key-Off — expected: Battery voltage should be present for at least 15 seconds after the ignition is turned off.. Failure: If voltage is not present, the TCM cannot complete its 'dither' self-test, potentially logging a false P0747 on the next startup.

Scan Tool Commands That Help

• GDS2 (GM Tech 2 successor): Transmission Service Fast Learn Procedure — This procedure is required after any significant transmission repair, including valve body or solenoid replacement, to allow the TCM to relearn clutch apply pressures and shift characteristics. Failure to perform this can result in poor shift quality even after a successful mechanical repair.
• GDS2 or other professional bi-directional scanner: Solenoid Active Test — Used to command a specific solenoid on and off while the vehicle is stationary to verify its electrical and mechanical response. A technician can listen for an audible click or monitor pressure data to see if the solenoid is functioning as commanded.

Wiring & Ground Locations

• BCM Connector X4, Pin 22 — The Body Control Module (BCM) is typically located inside the vehicle, often under the dashboard. For a Chevrolet Equinox (which shares platform elements), it's shown under the dash.. This specific pin provides a key voltage supply to the TCM. For the rare electrical fault described in TSB #PIP5697B, a technician must probe this pin after key-off to ensure it supplies voltage for at least 15 seconds, allowing the TCM to perform its solenoid self-test. A loss of this voltage can cause a false P0747.
• Solenoid Retaining Clips — Inside the transmission, on the valve body, holding each solenoid in its bore.. On GM 8, 9, and 10-speed transmissions, these clips can fatigue, allowing the solenoid to be pushed partially out of its bore. This creates a hydraulic leak, leading to pressure control issues and codes like P0746/P0747, even if the solenoid itself is perfectly functional. It is recommended to replace these clips any time the valve body is serviced.

Model Year Variations Within This Range

• 2024 models (specifically with transmission build dates from 10/1/2023 to 4/22/2024): These transmissions are subject to TSB #PIP5974A, which identifies a batch of out-of-round 1-2-3-4-5-6 clutch snap rings as the primary cause for P0747. For vehicles in this range, this mechanical defect is the highest probability cause, superseding other common causes like solenoid or valve body failure.