P0751 on GMC: How to Diagnose & Fix
Shift Solenoid A Performance/Stuck Off
4 GMC models · 4 documented issues · 3 critical · $150-$4,500 repair
P0751 on GMC by model: symptoms, diagnosis and fix
The 2010-2017 Terrain uses the GM 6T45 (2.4L) and 6T70 (V6) 6-speed automatic transmissions, both of which suffer from torque converter shudder, harsh shifts, and solenoid failures. The shudder occurs at light throttle between 30-50 mph when the torque converter clutch locks up. Solenoid pack wear causes P0756, P0751, and P0776 transmission fault codes. The transmission is sensitive to fluid condition — the 6T45/6T70 was originally filled with Dexron VI, and that early fluid degrades faster than newer formulations, so a full fluid exchange with current Dexron VI is the first step.
Common Symptoms
- Shudder at light throttle 30-50 mph
- Harsh 1-2 or 2-3 upshift
- Hesitation or lurch when pulling away from a stop
- Transmission fault codes P0756, P0751, P0776
- Check engine light
- Delayed engagement from Park to Drive when hot
How to Fix
Full fluid exchange with Dexron VI (ACDelco 10-9243 or equivalent). TCM calibration update. Solenoid pack replacement (GM 24272814) if codes present. Valve body replacement for internal failures. Fluid service every 40,000 miles recommended for stop-and-go use.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Dexron VI full-synthetic automatic transmission fluidOEMACDelco 10-9243 (GM 88865549)Cross-refValvoline DEXRON VI ATF 822405, Mobil 1 Synthetic ATF Dexron VI 112980, Castrol Transmax DEXRON-VI 03520C$8–$15
Dexron VI is required — do NOT substitute Dexron III or a universal/multi-vehicle ATF, as the friction
- Control solenoid valve assembly (valve body + solenoids + TEHCM) — 2.4L, 2012-2013OEM24041960$600–$960
THIS is the part that actually fixes P0751/P0756/P0776 on the 6T40/6T45. GM does not sell the individual shift/pressure-control solenoids for this transmission as a serviceable part — the solenoids are integrated into the TEHCM/valve bod…
- Control solenoid valve assembly (valve body + solenoids + TEHCM) — 2.4L, 2014-2017OEM24041961$598–$915
Same function as 24041960 but the correct number for the later 2.4L Terrain — this is the year split, so do not cross-order between them.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (2)
The Allison 1000 6-speed automatic transmission used behind the Duramax diesel in Sierra 2500HD/3500HD is widely regarded as extremely durable, but the Transmission Control Module (TCM) and solenoid pack do develop faults. Common issues include harsh 1-2 shifts, transmission sticking in one gear, slip codes, and the truck going into limp mode (3rd gear only). Using the wrong fluid or skipping fluid service is a common cause of premature solenoid wear. TCM software updates from GM address most calibration-related shift complaints.
Common Symptoms
- Harsh or clunky 1-2 upshift
- Transmission stuck in 3rd gear (limp mode)
- Delayed engagement from Park to Drive
- Slip or flare during 2-3 shift
- Check engine light with transmission codes (P0700, P0730, P0751)
- Transmission not shifting above 3rd gear under load
How to Fix
TCM software update at dealer. Fluid service (drain/fill every 30k miles, full exchange every 60k). Solenoid pack replacement (Allison 29539579). TCM replacement if software update fails. Use the GM-specified DEXRON-VI fluid (or an approved TES-295 fluid such as Allison TranSynd).
Sources for this issue (1)
On GMT800 Sierra 1500 trucks equipped with the 4L60-E family automatic, a well-known internal failure is cracking or stripping of the reaction sun shell. Owners commonly report sudden loss of reverse, 2nd gear and 4th gear after a bang or flare, while 1st and 3rd still work. This is widely documented in transmission rebuild literature, repair databases, and owner reports for GM trucks and SUVs using this transmission.
Common Symptoms
- loss of reverse
- no 2nd gear
- no 4th gear
- harsh bang followed by missing gears
- shifts from 1st straight to 3rd
- slipping on acceleration
How to Fix
Diagnosis usually starts with verifying gear loss patterns, checking line pressure, and scanning for ratio/performance codes before condemning the unit. Repair requires transmission removal and overhaul or replacement, typically installing an upgraded hardened sun shell such as the commonly recommended 'Beast' style shell along with inspection of clutches, band, pump, and valve body wear items.
Sources for this issue (2)
The 4L60E four-speed automatic in these trucks commonly fails in two ways. The first is a burnt 3-4 clutch pack. Transmission parts maker Sonnax traces most 3-4 slipping to low line pressure or to leaks in the third-gear oil circuit. Those leaks can come from input shaft seals, a leaking input drum, a clogged input housing checkball, a worn pump, a leaking 3rd accumulator checkball, worn accumulator pins, or worn valve body bores. The weak factory 3-4 backing plate also flexes when it applies, which builds heat. Heat can warp the 3-4 piston's rubber seal so oil pressure blows past it, and the clutches then slip and burn, so the truck slips in 3rd and 4th gear. The second failure is the sun (drive) shell. It can split in two, or the input gear can wear its internal splines smooth. Owners then report trouble shifting from 1st to 2nd or into reverse or overdrive, along with slipping and grinding noises.
Common Symptoms
- Slipping in 3rd or 4th gear
- No 3rd gear
- Harsh shifts
- Trouble shifting from 1st to 2nd or into reverse or overdrive, sometimes with grinding (sun shell)
- Burnt fluid
How to Fix
Start with the simple checks. Check the fluid level and condition, and scan for codes. Sonnax notes that faulty TP, MAP or MAF sensor readings, a bad EPC (pressure control) solenoid or voltage drops at the control module can all upset line pressure. On 1996 trucks, Sonnax says to verify the ground wire update in GM bulletin 00-07-30-026. To fix a burnt 3-4 pack or a broken sun shell, the transmission has to come out and be taken apart, which SlashGear describes as essentially a rebuild. During the rebuild, find the leak that burnt the clutches as well as replacing them. That means air-checking the loaded input drum, air-checking the input housing-to-shaft seal area, vacuum-testing the input housing checkball, and checking the pump passages, the 3rd accumulator checkball and the valve body bores. Replace both the 3-4 clutch pack and the 3-4 piston, fit a heavy-duty 3-4 backing plate (for example Sonnax 74140-01K), and replace the sun shell if it is cracked or its splines are worn. Owners report quotes of $1,700-$1,900 for a complete rebuild, and SlashGear says to expect at least $1,000-$2,000 for a 3-4 clutch and piston repair.
What you need to diagnose it
The repair instructions explicitly call for reading stored codes. Use a scanner that can read the named code families before choosing a repair.The recommended scanner supports these code families; confirm your exact year, model and module coverage before buying.
ANCEL AD310 Classic OBD-II Scanner
Read & clear engine (P) codes
$20–$40View
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Reading and clearing the code is DIY work. Module replacement or reprogramming is not — most modules are VIN-programmed, so a new one does nothing until a shop codes it to your car. Check for an open recall or service bulletin before buying anything.
Sources for this issue (2)
P0751 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 P0751 mean on a GMC?
P0751 stands for "Shift Solenoid A Performance/Stuck Off." This code means the transmission control module commanded Shift Solenoid A (sometimes called Shift Solenoid 1) but the transmission did not respond properly, with the solenoid acting as though it is stuck 'off.' Shift solenoids are electrically operated valves that direct hydraulic fluid pressure to engage gears, so when one underperforms the transmission may shift harshly, slip, or fail to change gears at the right time. The computer sets this code when the measured gear ratio or shift behavior does not match the commanded state. It generally indicates a hydraulic or performance issue with the solenoid or the fluid circuit it controls inside the automatic transmission. On GMC it is documented across 4 models: Terrain, Sierra 2500HD, Sierra 1500, C/K 1500.
What are the most common causes of P0751?
The most common causes of P0751 are: Stuck or failed Shift Solenoid A, Low, dirty, or degraded transmission fluid, Clogged solenoid screen or valve body passages, Sticking or worn valve body components, Wiring or connector problem at the solenoid, Internal transmission mechanical wear, Faulty transmission control module. The specific cause varies by vehicle.
How much does it cost to fix P0751 on a GMC?
Published repair estimates on GMC range from $150 to $4,500 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.