The 6L80 is the transmission most Silverado 1500 owners are driving if their truck has a six-speed automatic. GM lists it by its RPO code, MYC, in every bulletin that touches it, and the Silverado shows up in almost all of them. It is a strong unit for its size, but it has a handful of failures that come back again and again, and each one tends to line up with a certain span of model years. If you know which year you are looking at, you usually have a short list of suspects before the pan comes off.
This post sticks to what GM itself has published about the 6L80 in the Silverado, plus what the converter rebuilders at Sonnax have found inside these units. For the transmission-wide picture, our 6L80 common problems guide covers the full list. Here I am going year by year through the half-ton truck.
The short version: 2007-2008 Silverados can crack the welded 1-2-3-4 / 3-5-R clutch housing (GM bulletin 09-07-30-004J). A 2011 AFM V8 that shudders in V4 mode with TCC slip stuck at a constant 0 rpm likely has a broken TCC regulator valve spring (PI1413). 2013-2021 Silao-built units can leak at the stator support gasket and cause slips, launch shudder and a 1-2 clunk (PIP5175F). A 2015-2016 truck with no 4th, 5th or 6th, P0796 and a clean pan has a broken 4-5-6 hub, not a bad TEHCM (16-NA-027). And the full-size 300 mm converter fails at a high rate and loads the unit with metal (Sonnax).
First: Confirm the Truck Has a 6L80
Not every Silverado 1500 has one. Earlier trucks and many V6 trucks used the four-speed 4L60E or 4L65E, and later trucks moved to the 8L90 or 10L80. Bulletin 09-07-30-004J lists the 2007-2008 Silverado with the 6L80 (RPO MYC), and GM's shudder bulletin 20-NA-142 covers Silverado 1500 trucks through the 2022 model year with MYC or MYD. The only way to know for sure on a given truck is the Service Parts Identification label in the glovebox: look for MYC. If you find a four-speed code instead, our 4L65E Silverado 1500 problems post is the one you want.
| Model years (per GM) | Known 6L80 problem | GM document |
|---|---|---|
| 2007-2008 | Cracked 1-2-3-4 / 3-5-R housing weld; slips in reverse, P0776, P2715, P2723 | 09-07-30-004J |
| 2006-early 2009 | One-piece pump cover seal rings leak; harsh 2-3 shift | 09-07-30-004J |
| 2011 (AFM V8) | Broken TCC regulator valve spring; shudder in V4 mode | PI1413 |
| 2013-2021 (Silao, source code 2) | Loose stator support bolts / gasket leak; slip, launch shudder, 1-2 clunk | PIP5175F |
| 2015-2016 | Broken 4-5-6 clutch hub; no 4th-6th, P0796 | 16-NA-027 |
| 2015-2022 | Depleted fluid additives; shudder or surge | 20-NA-142 |
1. 2007-2008: The Cracked Clutch Housing
What the owner says: it slips or will not go when put in reverse, reverse engagement is slow, the 2-3 shift is harsh, it slips in fifth, or it slips under acceleration when passing. The check engine light is on.
Why it happens: GM bulletin 09-07-30-004J names the 2007-2008 Silverado and points to a cracked weld on the 1-2-3-4 / 3-5-R clutch housing. That housing feeds two clutch packs, so a crack bleeds apply pressure and the TCM sees the slip. The codes GM lists are P0776, P2715 and P2723.
How to check it: GM's test is simple and does not need special tools. With the housing out, put soap compound on the weld, hold your thumb over the air bleed passage and blow compressed air into the 3-5-R clutch feed hole. Bubbles at the weld mean a new housing. GM now sells the housing fully assembled with pistons, seals, clutches and bearing (part 24238694 for MYC 2008-up).
Two warnings straight from the bulletin. First, GM changed the 1-2-3-4 piston, its housing and the 3-5-R piston for the 2008 model year, and dropping a 2008 complete housing into a 2007 or older 6L80 can cause a 2-3 flare or 3-5-R clutch distress. Second, a new housing in a 2007 or older unit needs all three inner seals installed, or you get no reverse, no forward or burnt clutches.
The same bulletin covers a harsh 2-3 shift on 2006 to early 2009 units: the pump cover used one-piece seal rings for the 1-2-3-4 and 3-5-R circuits until December 2008, when GM switched to a two-piece design. The one-piece rings can leak and cause a harsh 2-3, usually at low mileage. GM says to replace them with new one-piece rings, installed in the correct direction, and not to put one-piece rings in a two-piece cover. More on this failure is in our 6L80 3-5-R clutch failure post.
2. 2011 AFM V8: Shudder in V4 Mode
What the owner says: a vibration or roughness at low, steady speed on a level road, worse going up a slight grade. It feels like rumble strips.
Why it happens: GM Preliminary Information PI1413 covers the 2011 Silverado and other trucks with an Active Fuel Management V8 and the 6L80. The root cause GM gives is a broken torque converter clutch regulator valve spring (item 353) in the lower valve body. With the spring broken the TCC clamps solid, slip drops to zero, and the engine's V4 pulses come straight through the driveline.
How to check it: this one is a scan tool diagnosis. Drive at a steady throttle in V4 and watch TCC slip speed. GM says it is normal for slip to drop to zero for a moment and then come back up to 30-50 rpm. If it sits at a constant 0 rpm during the shudder, pull the lower valve body and look for the broken spring. GM's fix is a new lower valve body; a rebuilder can replace the spring and valve instead if the bore is good.
Sonnax TCC Regulator Valve Spring 104740-45K for the 6L80
The spring GM's PI1413 points to on a 2011 AFM truck that shudders in V4 with TCC slip stuck at zero. Check the valve and bore while you are in there.
Shop the TCC regulator spring →Need a different part? Browse the full 6L80 parts collection.
3. 2013-2021: Stator Support Gasket Leak on Silao Units
What the owner says: delayed engagement into Drive, a shudder on launch, slipping into 1st, 2nd, 3rd or 4th, or a bump or clunk on the 1-2 shift. Usually only once it is fully warm.
Why it happens: GM's PIP5175F (February 2025, replacing PIP5175E) lists the 2013-2021 Silverado and the 2019-and-later Silverado LD/Limited with 6L80 MYC units built in GM's Silao, Mexico plant 2, identified by source code 2 on the transmission ID. The cause GM gives is loose stator support to pump cover bolts, which lets the stator support gasket leak. The stator support carries apply oil to the 1-2-3-4 clutch, so a leak there shows up as slips in the gears that use it.
How to check it: if normal diagnosis does not turn up the cause, GM says to drop the pan, remove the control assembly and apply compressed air to the 1-2-3-4 clutch apply passage. Look for air coming out of the compensator feed passage in the pump cover, and listen for heavy air leakage inside the case. You can also look up between the pump stator support and the 1-2-3-4 / 3-5-R housing for a misaligned gasket.
The bolt check is where people go wrong. GM says never to check these bolts with a wrench or ratchet, because they are torqued at the factory and not meant to be loosened. Use your fingers, or just a socket and your fingers, and try to turn them counterclockwise. If any bolt is loose or the gasket is out of place, GM's fix is a new pump cover (kit 24248573), and the 1-2-3-4 clutch plates need inspection. Reset the transmission adapts after the repair. Our 6L80 delayed engagement guide covers the other causes of slow engagement.
4. 2015-2016: No 4th, 5th or 6th With P0796
What the owner says: the truck runs fine in town but will not go past third, and the check engine light is on.
Why it happens: GM bulletin 16-NA-027 covers the 2015-2016 Silverado with the 6L80. The cause is a broken 4-5-6 clutch hub, which comes as one assembly with the output carrier shaft (item 475). The 4-5-6 clutch is applied in 4th, 5th and 6th, so with the hub broken the truck has only 1st through 3rd and reverse, and the TCM sets P0796.
The tell: GM says the pan will be clean with little or no debris and the fluid will look clean too. That is unusual for a no-upshift complaint, and it is exactly what makes this one easy to get wrong. GM's bulletin goes out of its way to say that if the hub is broken, the TEHCM (control solenoid valve assembly with TCM) is not the cause and should not be replaced. A shop that sees P0796 with clean fluid and orders a TEHCM is throwing away several hundred dollars. The repair is the hub and shaft assembly, which is a transmission-out job.
5. Shudder or Surge on a Low-Mileage Truck
What the owner says: a surge or shudder while cruising, often reported as converter shudder.
Why it happens: GM bulletin 20-NA-142 (May 2022) covers Silverado 1500 trucks from 2015 through 2022 with the MYC or MYD transmission. GM states the cause is that additives in the fluid may have been depleted during operation, and some of those additives help keep clutch slip rates consistent.
The fix and its limit: the bulletin only applies to trucks at 30,000 miles (50,000 km) or less. GM's procedure is to pull the pan first. If there is metallic debris, the converter and filter get replaced. If not, the transmission gets three fills of 6 quarts of DEXRON VI, running it through all six forward ranges, reverse and neutral between drains, with a new filter on the last drain. On the fill-tube version of the procedure, the cooler line bolt goes back at 22 N·m (16 lb-ft) with a new cooler line seal. Over 30,000 miles, GM says to replace the torque converter and filter per service information instead of doing the exchange. That line matters: on a high-mileage Silverado, a fluid exchange is not GM's answer to a shudder. Our 6L80 TCC shudder diagnosis post walks through separating converter shudder from engine and driveline vibration.
6. The Converter That Takes the Transmission With It
What the owner says: slipping with occasional clunks, check engine light on.
What you find: Sonnax describes the pattern its converter-rebuilding customers see on full-size 6L80 trucks: P0741, TCC slip far out of range on the scan tool, and a pan full of debris. On teardown the unit is loaded with metal and the pump in the bell housing is worn enough to need machining or replacement. The source is the converter.
Most full-size trucks with a 6L80 use the 300 mm JMBX converter, a single-disc, non-captive clutch design. Sonnax reports that a high percentage of these show the clutch piston and front cover crashing into each other, and that this is where the metal in the transmission comes from. Their fix on the converter side is a forged front cover (GM-CC-13) and forged piston (GM-DA-17P). Sonnax notes it sells many more forged covers for the 6L80/90 converter than for the similar 4L60E unit.
What that means on a Silverado: if a 6L80 comes in with P0741 and metal in the pan, plan on more than a converter. Check line pressure, inspect the pump and bell housing pocket for scoring, flush and flow-test the cooler, and send it out with a converter built to survive. A rebuild with a stock-style converter and a dirty cooler is the classic comeback. Our 6L80 P0741 guide has the line pressure and slip-speed checks.
A Quick Diagnostic Order for a Silverado 6L80
- Confirm MYC on the glovebox label and note the model year. Match the year against the table above.
- Pull codes and freeze frame. P0776/P2715/P2723 on a 2007-2008 points at the housing; P0796 on a 2015-2016 points at the 4-5-6 hub; P0741 on any year means check line pressure before blaming the converter alone.
- Road test with the scan tool on TCC slip speed. Constant 0 rpm during a shudder on a 2011 AFM truck points at the TCC regulator spring; normal is a momentary drop then 30-50 rpm.
- Drop the pan before you order parts. Clean pan with a no-4th-6th complaint fits 16-NA-027. Metal points at the converter and pump.
- For warm-only slips and a 1-2 clunk on a 2013-2021 Silao unit, air test the 1-2-3-4 apply passage per PIP5175F before you tear the unit down.
Keep the numbers at the bench. Our free transmission fluid spec chart lists the correct ATF for the 6L80 and dozens of other units, so nobody tops off a Silverado with the wrong fluid.
FAQ
What years of Silverado 1500 have the 6L80 transmission?
GM bulletins list the 6L80 (RPO MYC) in the Silverado from the 2007-2008 model years (bulletin 09-07-30-004J) through the 2019-2022 Silverado LD and Limited, and bulletin 20-NA-142 covers Silverado 1500 trucks through 2022. Not every truck in that span has one, since V6 and earlier trucks used four-speeds and later trucks moved to the 8L90 or 10L80. Check the glovebox label for MYC.
Why does my 2015 or 2016 Silverado not shift past third gear?
GM bulletin 16-NA-027 says a no 4th, 5th and 6th condition with DTC P0796 on 2015-2016 Silverado 6L80 trucks may be a broken 4-5-6 clutch hub with output carrier shaft. The pan and fluid are usually clean. GM says the TEHCM is not the cause in that case and should not be replaced.
What causes a 6L80 shudder in a Silverado 1500?
On a 2011 AFM V8 truck, GM's PI1413 points to a broken TCC regulator valve spring when TCC slip sits at a constant 0 rpm in V4 mode. On 2015-2022 trucks under 30,000 miles, GM bulletin 20-NA-142 blames depleted fluid additives and calls for three DEXRON VI fills. Above 30,000 miles GM says to replace the converter and filter instead.
Is the 6L80 in the Silverado reliable?
It is a strong unit, but it has documented weak points tied to certain years: the cracked clutch housing on 2007-2008 trucks, stator support gasket leaks on 2013-2021 Silao-built units, the broken 4-5-6 hub on 2015-2016 trucks, and the full-size converter that Sonnax reports fails at a high rate. Knowing the model year narrows the diagnosis fast.
Sources
- General Motors — Service Bulletin 09-07-30-004J, "Slips in Reverse or Third, Delayed Reverse or Drive Engagement, DTC P0776, P2715, P2723, Harsh 2-3 Shifts," February 2014 (hosted by NHTSA). Backs: 2007-2008 Silverado with 6L80 (MYC) coverage, the cracked 1-2-3-4 / 3-5-R housing cause and symptom list, the soap-and-air weld test, part 24238694, the 2008 design change warning, and the one-piece to two-piece seal ring change in December 2008. GM bulletin 09-07-30-004J (PDF)
- General Motors — Preliminary Information PI1413, "Diagnostic Tip for Vibration, Shudder or Roughness While Driving at Low Steady Speeds in V4 Mode," February 2015 (hosted by NHTSA). Backs: 2011 Silverado AFM V8 with 6L80 coverage, the broken TCC regulator valve spring (353) cause, constant 0 rpm TCC slip versus normal 30-50 rpm, and lower valve body replacement. GM PI1413 (PDF)
- General Motors — Preliminary Information PIP5175F, "Slip Or Shudder During A Launch In First Second Third Or Fourth Gears, Delayed Engagement Into Drive, Clunk Or Bump During The 1-2 Shift," published February 3, 2025 (hosted by NHTSA). Backs: 2013-2021 Silverado and 2019-up Silverado LD/Limited Silao plant 2 (source code 2) coverage, the stator support bolt and gasket leak cause, the compressed-air test, the finger-only bolt check, pump cover kit 24248573 and the adapt reset. GM PIP5175F (PDF)
- General Motors — Service Bulletin 16-NA-027, "Diagnostic Tip for No Fourth, Fifth and Sixth Gears and/or MIL Illuminated with DTC P0796," February 2016 (hosted by NHTSA). Backs: 2015-2016 Silverado 6L80 coverage, the broken 4-5-6 clutch (with output carrier shaft) hub cause, the clean pan and fluid tell, and GM's instruction not to replace the TEHCM. GM bulletin 16-NA-027 (PDF)
- General Motors — Service Bulletin 20-NA-142, "Shudder/Surging While Driving," May 2022 (hosted by NHTSA). Backs: Silverado 1500 2015-2022 MYC/MYD coverage, the depleted-additive cause, the 30,000-mile limit, the three 6-quart DEXRON VI fills, the metallic-debris converter replacement rule and the 22 N·m (16 lb-ft) cooler line bolt. GM bulletin 20-NA-142 (PDF)
- Sonnax — "6L80, 6L90 Transmission Tech Advisory: Consider an Updated Converter in Your Next Rebuild," March 31, 2020. Backs: the P0741 / debris / worn pump pattern on full-size 6L80 trucks, the 300 mm JMBX single-disc converter, piston-to-cover contact as the metal source, and the forged GM-CC-13 cover and GM-DA-17P piston. sonnax.com/tech_resources/845