P0751 on 2015-2019 GMC Savana: Shift Solenoid 'A' Causes and Fixes

What's Unique About the 2015-2019 Gmc SAVANA

General Motors has specifically identified a problem on this platform (and many others using the 6L-series transmissions) where the Clutch Select Solenoid Valve 2 can stick internally. This known issue, documented in Technical Service Bulletins (TSBs), makes the solenoid itself the primary suspect, more so than on other vehicles where wiring or fluid issues might be equally likely. The problem leads directly to the symptoms described by owners, such as slipping from a stop, poor acceleration, and feeling like the van is starting in a high gear.

Diagnostic Flowchart

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

Symptoms You May Notice

• Reduced acceleration at low speed.
• Transmission slipping when accelerating from a stop.
• Vehicle feels like it is starting in a higher gear (e.g., 4th gear).
• Harsh or delayed gear shifts.
• Transmission gets stuck in one gear (limp mode).
• Check Engine Light is on.
• Reduced fuel economy.
• Transmission may overheat.

Most Likely Causes

1. Sticking Clutch Select Solenoid Valve 2 (Shift Solenoid 'A') 🔴 High Probability This is a known issue documented by GM in TSBs #PI1344B and #PI1344C 🎬 Watch: Expert breakdown of the P0751 code and GM TSBs., which state this specific solenoid is prone to sticking in its bore within the lower valve body of 6L80/6L90 transmissions.
   How to confirm: A technician can command the solenoid on and off with a bi-directional scan tool to check its response. TSB PI1344C also details a solenoid performance test using compressed air. Visual inspection after removal may show scratches on the valve, which confirms the issue.
   Typical fix: Replace the faulty shift solenoid. Per TSB PI1344C, if the valve is stuck or shows any scratches, the entire lower valve body should be replaced. Many technicians recommend replacing the full solenoid pack/assembly while the pan is off.
   Est. part cost: $40-$80 for a single aftermarket solenoid, though OEM replacement may require a full solenoid pack or valve body assembly costing several hundred dollars.
2. Low or Dirty Transmission Fluid 🟡 Medium Probability
   How to confirm: Check the transmission fluid level and condition. On these transmissions, this is done via a fill plug on the pan as there is no dipstick. The fluid should be at the correct level, red in color, and not smell burnt. Dark, dirty, or fluid containing debris indicates a problem.
   Typical fix: Perform a transmission fluid and filter change using DEXRON VI fluid. If the fluid is heavily contaminated with metal shavings, a transmission flush or further diagnosis is needed as this may indicate a more severe internal failure.
   Est. part cost: $60-$150 for fluid and a new filter.
3. Faulty Wiring or Connector ⚪ Low Probability
   How to confirm: Visually inspect the main wiring harness connector at the transmission case for any signs of damage, corrosion, or loose pins. The internal harness leading to the solenoid can also be a failure point, which requires removing the pan to inspect.
   Typical fix: Repair the damaged section of wiring or replace the corroded connector. In some cases, the internal transmission wiring harness may need replacement.
   Est. part cost: $20-$200 depending on the extent of the damage.

Rare But Worth Checking

• Faulty Transmission Control Module (TCM): This is rare and should only be considered after all other possibilities have been ruled out. On 6L80/6L90 transmissions, the TCM (sometimes called TEHCM) is located inside the transmission, mounted to the valve body. Failure often presents with other communication codes (U-codes) in addition to P0751.
• Clogged Valve Body Passages: Debris from normal wear can clog the small passages in the valve body that the solenoid controls. This requires removing and cleaning or replacing the entire valve body, a complex job. 🎬 Watch: Detailed tear down of the 6L80 valve body assembly. The TSB for P0751 specifically points to the solenoid valve itself sticking in its bore as the primary cause.

Diagnosis Steps

1. Check the transmission fluid level and condition. This requires raising the vehicle and removing a fill plug, as there is no dipstick. Top off or change if necessary, using only DEXRON VI fluid.
2. Use an OBD-II scanner to check for other transmission-related codes, especially P0700.
3. Connect a bi-directional scan tool to command the Shift Solenoid 'A' (PC Solenoid 2) on and off to test its mechanical function.
4. If the solenoid doesn't respond or tests fail, drain the transmission fluid and remove the transmission pan to access the valve body and solenoids.
5. Visually inspect the wiring and connectors inside the pan for any obvious damage.
6. Follow TSB PI1344C procedure: remove the lower valve body and inspect the Clutch Select Solenoid Valve 2. Check for scratches on the valve or if it is stuck in the bore.
7. If the valve is scratched or damaged, replace the lower valve body as recommended by GM. If it appears okay, test the solenoid's resistance with a multimeter. An open or shorted reading confirms a bad solenoid.
8. If wiring and the solenoid are confirmed good, the issue may be a blockage in another part of the valve body or a faulty TCM.

Parts You'll Likely Need

• Automatic Transmission Control Valve Solenoid (Shift Solenoid A/1-2 or Clutch Select Solenoid 2) (OEM #Typically sold as part of a solenoid kit or valve body assembly. A single solenoid is not always offered by GM.) — This is the most common failure point for code P0751 on this vehicle, as identified in GM service bulletins.
  Trusted brands: ACDelco
  OEM price range: $300-$600 (for assembly)
  Aftermarket price range: $30-$80 (for single solenoid)
• Automatic Transmission Filter Kit (OEM #e.g., ACDelco 24236933 (check specific application)) — The transmission pan must be removed for the repair, so the filter and pan gasket should always be replaced at the same time.
  Trusted brands: ACDelco, Wix, ATP
  OEM price range: $40-$70
  Aftermarket price range: $20-$40
• DEXRON VI Automatic Transmission Fluid (OEM #ACDelco 10-9243) — The fluid must be drained to perform the repair and should be replaced with new, clean fluid to ensure proper transmission function. The 6L80/6L90 requires this specific fluid.
  Trusted brands: ACDelco
  OEM price range: $8-$12 per quart
  Aftermarket price range: $6-$10 per quart
• Lower Valve Body — TSB PI1344C recommends replacing the entire lower valve body if the Clutch Select Solenoid Valve 2 shows any signs of scratching or damage upon inspection.
  Trusted brands: ACDelco (GM Genuine)
  OEM price range: $400-$800

Related Codes That Often Appear With This One

• P0756 — This code is for Shift Solenoid 'B' Performance. It's common to see codes for other solenoids if the root cause is dirty fluid, a failing internal harness, or a failing TCM affecting multiple components.
• P0700 — This is a generic transmission fault code that simply indicates the TCM has stored a specific fault code (like P0751). It's an informational code that points the technician to the transmission system.

Technical Service Bulletins (TSBs) & Recalls

• PI1344C
• PI1344B

Platform-Specific Known Issues

• A known condition exists where the Clutch Select Solenoid Valve 2 may stick in its bore, causing reduced acceleration and/or transmission slipping from a launch, which sets DTC P0751.
• This condition can be very intermittent and result in the transmission starting in 4th gear from a stop.
• GM's official recommendation per TSB PI1344C is to inspect the valve for scratches; if any are found, the entire lower valve body must be replaced, not just the solenoid.

Mechanic-Grade Diagnostic Values

• Shift Solenoid (On/Off type) resistance — expected: 20 - 40 Ohms. Failure: A reading of infinite (open circuit) or near zero (short circuit) Ohms indicates a failed solenoid.
• Pressure Control Solenoid (PWM type) resistance — expected: 3 - 8 Ohms. Failure: A reading outside this range indicates a failed solenoid.
• Shift Solenoid (On/Off type) current draw — expected: 0.3 - 0.7 Amps at 12V. Failure: Incorrect amperage reading indicates a failed solenoid.
• Solenoid power supply voltage — expected: ~12.6V (Battery Voltage). Failure: A voltage drop greater than 0.5V suggests a wiring or ground issue.

Scan Tool Commands That Help

• GM GDS2 / MDI2 or equivalent J2534 device: Service Fast Learn Adapts — This procedure is mandatory after replacing the TEHCM, valve body, or entire transmission. It resets and relearns clutch fill volumes and shift timing. Failure to perform this can result in harsh shifts, slipping, and premature wear.
• GM GDS2 / MDI2 or equivalent J2534 device: Solenoid Activation / Output Control — Used to command a specific solenoid on and off while the engine is running to verify mechanical response. When used with a test plate on the bench, a technician can check for correct air pressure release, confirming the solenoid is not stuck.
• GM GDS2 / MDI2 or equivalent J2534 device: TCM Programming — When installing a new or remanufactured TEHCM, it must be flashed with the vehicle's specific VIN and the correct calibration file from GM's service site. The vehicle will not start or shift correctly until this is done.

Wiring & Ground Locations

• External Transmission Connector — On the passenger side of the transmission case, where the main vehicle harness connects to the transmission's internal harness.. This 16-pin connector is a critical point for all communication between the vehicle and the TEHCM. Corrosion or damage from heat can cause intermittent connection loss, triggering various transmission codes, including P0751. A common repair involves replacing the pigtail (p/n 350-0168 is a known repair kit).
• Chassis and Engine Block Grounds — Multiple points connecting the negative battery cable to the vehicle frame/chassis and the engine block.. The TEHCM relies on a solid ground connection through the engine and chassis. A corroded or loose ground can cause erratic behavior, voltage drops, and communication errors that may be misdiagnosed as an internal TEHCM or solenoid failure.

Real Owner Repair Stories

• Reddit user in r/Silverado (2015 GM Truck with 6L80 transmission, failed at 110k miles) — Transmission failure.
  ❌ Tried (didn't work) Waiting past the 100k mile warranty.
  ✅ What actually fixed it The root cause was identified as a failed torque converter. The entire transmission had to be replaced (in this case, with a Jasper remanufactured unit). This highlights how torque converter failure can introduce debris that leads to solenoid codes and eventual transmission death.
• Reddit user in r/Silverado (GM Truck with 6L80 transmission) — General transmission problems and failure.
  ❌ Tried (didn't work) Standard transmission rebuilds that don't address the root cause.
  ✅ What actually fixed it The user noted that the torque converter is programmed by GM to constantly slip under certain conditions for smoothness, which wears out the clutch material, contaminates the fluid, and destroys the transmission. The recommended long-term fix is to use a tuner (like HP Tuners) to disable this feature in lower gears and command a full lockup, combined with installing a more durable billet torque converter.

OEM Part Supersession History

• Various, e.g., 24256939, 24259835 → Various, e.g., 24275873, GM6L-TEHCM-C6 (Sonnax Reman) — GM has revised the TEHCM (the assembly containing the TCM and solenoids) multiple times to address component failures and update software logic.
  Heads up: TEHCMs are NOT interchangeable between years or models without correct programming. They are identified by a 'Tag ID' and must be programmed with the specific vehicle's VIN and calibration file. Installing the wrong TEHCM can result in a no-start condition, immediate limp mode, or other faults.

Model Year Variations Within This Range

• 2015-2019: While the core issue with the P0751 solenoid remains consistent, the specific TEHCM hardware and software ('Tag ID') can vary by model year and vehicle application (6L80 vs 6L90). When replacing the TEHCM, it is critical to source the correct part for the vehicle's VIN and ensure it is programmed with the latest calibration, as an incorrect module will not function properly.