Allison 1000 reliability: years to avoid, problems & recalls

By CarWhere Research · Updated

The Allison 1000 six-speed (GM RPO MW7) paired with the Duramax diesel in Silverado and Sierra HD pickups shows up in GM's records mainly through service bulletins rather than recalls: electrical issues that cause lost TCM communication on 2007–2012 trucks, binding shift solenoids on 2012–2013 trucks and a chafing TCM harness on 2015–2016 trucks. GM's 2024 Silverado HD announcement describes the Allison 10-speed that followed it.

Allison 1000 at a glance

Allison 1000 six-speed automatic (GM heavy-duty pickups, Duramax diesel): key facts
FactDetail
TypeConventional automatic
Forward speeds6
Built byAllison Transmission
Used byChevrolet, GMC
Years in useDocumented here in 2007–2019 Silverado and Sierra HD pickups with the Duramax diesel
Also known asA1000, MW7
Transmission-related NHTSA recalls listed0
Warranty extensions / special coverage listed0
Court settlements listed0

What the Allison 1000 is

The Allison 1000 is a heavy-duty automatic from Allison Transmission, whose 1000 Series units have five or six forward gears depending on the model. In GM heavy-duty pickups it carries the RPO code MW7: GM's 2015 Silverado HD service guide lists the Allison 1000 six-speed behind the 6.6L Duramax diesel, while gasoline HD trucks used GM's own Hydra-Matic 6L90.

GM bulletins describe features such as Tow/Haul mode and driver shift control and document a handful of service conditions, most of them electrical. From the 2020 model year the Duramax HD trucks moved to the Allison-branded 10-speed (10L1000), which is covered on the GM 10-speed page, including recall 24V-797.

Which vehicles use the Allison 1000?

Makes, models and model years equipped with the Allison 1000
MakeModelModel yearsNotes
ChevroletSilverado 2500HD / 3500HD2007–2019 (Duramax diesel)Allison 1000, RPO MW7; gasoline HD trucks used the 6L90 6-speed. Later trucks moved to the Allison-branded 10-speed[1][2][3][4][5][6]
GMCSierra 2500HD / 3500HD2007–2019 (Duramax diesel)Allison 1000, RPO MW7[2][3][4]

Known Allison 1000 problems

Lost TCM communication, hesitation or stuck in gear (2007–2012)

GM bulletin PI0310B covers Silverado and Sierra trucks with the Allison A1000 that intermittently hesitate, clunk, get stuck in gear or neutral, won't shift, or go into reduced torque, with codes P0880 and/or U0101. GM lists causes including resistance in the G102 engine ground and electrostatic discharge from certain aftermarket serpentine belts, and directs technicians to repair the ground, install an OEM belt and, where needed, relocate the TCM.[3]

Reported symptoms

  • Intermittent hesitation or clunk
  • Stuck in gear or neutral, won't shift
  • Codes P0880 or U0101

Service engine light from a binding shift solenoid (2012–2013)

GM bulletin PIP5060 covers 2012–2013 Silverado and Sierra HD trucks with the Allison (RPO MW7) showing a service engine soon light, no shift, wrong-gear starts or range inhibit with shift-solenoid codes. GM says the affected shift-solenoid armature may be binding; the fix is replacing the solenoid and, if the condition returns, cleaning the valve body.[7]

Reported symptoms

  • Service engine soon light
  • No shift or wrong-gear starts
  • Codes P0751/P0752, P0756/P0757 or P0761/P0762

MIL on and poor shifting from a chafed TCM harness (2015–2016)

GM bulletin PI1522 covers 2015–2016 Silverado and Sierra trucks with the Allison 1000 (RPO MW7) where the TCM wiring harness can rub against the engine accessory drive belt and be damaged, turning on the malfunction indicator lamp and degrading shift quality. The fix is to repair the harness and tie it away from the belt. GM notes the A1000's hydraulic default ranges are 1st, 3rd, 5th and reverse.[8]

Reported symptoms

  • Malfunction indicator lamp on
  • Poor shift quality or the transmission holding a default gear

Wrong software on some 2014 trucks (GM recall bulletin 13442A) (2014)

GM recall bulletin 13442A says 28 2014 Silverado HD and Sierra HD trucks with the Allison A1000 were reprogrammed by dealers with 2015 model-year software released by mistake, so the shift display did not show when the lever was moved to the 1 position, a failure to meet FMVSS 102. Dealers reprogrammed the TCM with the correct software.[9]

Reported symptoms

  • Shift-position display does not show the selected 1 position

Buying a used car with the Allison 1000: what to check

  1. Confirm the truck is a Duramax diesel with RPO MW7 on the glovebox label; gasoline HD trucks of the same years used a different transmission.
  2. Check for an aftermarket serpentine belt or added accessories (second alternator, pump); GM links some TCM communication faults to them.
  3. Ask for transmission fluid and filter service records; GM's Duramax owner supplement schedules transmission fluid and filter changes for the HD six-speed Allison.
  4. On 2015–2016 trucks, look at the TCM harness routing near the accessory belt for chafing.
  5. Run the VIN through NHTSA's recall lookup for any open campaigns on the truck.

Related research

Engines and model known-issues pages

Compare other transmissions

All transmissions: reliability and years to avoid

Frequently asked questions

Which trucks have the Allison 1000?

GM documents the Allison 1000 six-speed (RPO MW7) behind the Duramax diesel in Chevrolet Silverado and GMC Sierra 2500HD/3500HD pickups; GM bulletins cited here cover 2007–2016 trucks and GM's 2019 Duramax supplement still lists the HD six-speed Allison. Gasoline HD trucks used GM's 6L90 instead.

What problems does GM document for the Allison 1000?

GM's bulletins describe mostly electrical issues: lost TCM communication and stuck-in-gear complaints on 2007–2012 trucks tied to a ground connection or aftermarket belts, binding shift solenoids on 2012–2013 trucks, and a TCM harness that can rub the accessory belt on 2015–2016 trucks.

Has the Allison 1000 been recalled?

GM recall bulletin 13442A covered 28 2014 Silverado HD and Sierra HD trucks that received the wrong transmission software, which dealers corrected. The other GM documents cited here are service bulletins, not recalls. Check any truck's VIN with NHTSA for open recalls.

What replaced the Allison 1000 in GM trucks?

GM's newer heavy-duty pickups use the Allison-branded 10-speed (10L1000). Chevrolet's 2024 Silverado HD announcement says the Allison 10-speed became standard with both the 6.6L gas V8 and the Duramax diesel. 2020–2022 diesel HD trucks are part of recall 24V-797.

How CarWhere compiled this page

Every problem, recall, warranty extension and settlement above is CarWhere’s own summary of a primary record — NHTSA recall campaigns, manufacturer service bulletins and warranty-extension notices filed with NHTSA, manufacturer press material, and court or settlement-administrator records — and is numbered to its source below. We list a model year under “years to avoid” only when a manufacturer, regulator or court record ties it to the transmission. Complaint counts come from NHTSA’s public owner-complaint data, counted once per complaint. We do not estimate failure rates or repair costs. See also the years-to-avoid methodology.

Sources

Descriptions are CarWhere’s own summaries of the records below. Recall details are as reported to NHTSA by the manufacturer.

  1. 2016 Chevrolet Silverado 2500HD specifications — General Motors (media.gm.com)
  2. GM PI1197 (Mar. 2014): 2015 Silverado HD and Sierra HD new model features and service guide — General Motors (via NHTSA)
  3. GM PI0310B (Dec. 2011): Loss of communication with Allison TCM, hesitation, stuck in gear (2007–2012 Silverado/Sierra, A1000 RPO MW7) — General Motors (via NHTSA)
  4. 2019 Chevrolet/GMC Duramax Diesel owner manual supplement — General Motors
  5. 1000 Series and 2000 Series transmissions — Allison Transmission
  6. 2024 Chevrolet Silverado HD Hauls in More Power, Enhanced Interior and Smarter Technology — Chevrolet (General Motors) newsroom
  7. GM PIP5060 (Sept. 2012): 2012–2013 Silverado/Sierra 2500HD and 3500 with Allison transmission — service engine soon light — General Motors (via NHTSA)
  8. GM PI1522 (Aug. 2015): MIL on, poor transmission shift performance (2015–2016 Silverado/Sierra, Allison 1000 RPO MW7) — General Motors (via NHTSA)
  9. GM Recall Bulletin 13442A (Jan. 2014): Transmission control module — 2014 Silverado HD/Sierra HD with Allison A1000 — General Motors (via NHTSA)

Independent reference compiled by CarWhere Research — not affiliated with or endorsed by any manufacturer or transmission supplier. Product and model names are trademarks of their owners.