2020–2022 GMC Sierra: 10-speed harsh shifts or momentary rear-wheel lockup (diesel)
Likely causes, ranked
- Worn transmission control valve (software monitor, then valve body work under GM coverage)$0–$0Shop
- Repair done incorrectly under the first recall (re-recalled)$0–$0Shop
Real-owner fix counts will appear here as reports come in.
DIY or shop: See DIY or shop section
Parts to check
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Symptom: Harsh downshifts and, rarely, a momentary rear-wheel lockup when downshifting from eighth gear. After the recall software is installed, the truck may limit itself to fifth gear with a reduced-propulsion message.
Likely causes
- A worn control valve on 3.0 Duramax trucks. The recall software monitors for it, and GM's special coverage pays for the valve repair.
- Earlier recall repairs that need redoing (26V083).
Cost
$0 under the recall and GM's coverage.
DIY or shop?
Dealer only.
Useful steps
- Check your VIN for both recalls.
- If you see a reduced-propulsion message, ask the dealer about code P0747 and the special coverage.
Vehicle focus: 2020–2022 GMC Sierra.
Safety / mechanic note
A rear-wheel lockup can cause a loss of control. Verify with a dealer now.
Related trouble codes
- P0747
Recalls & service bulletins
Recalls
- 24V797000 2020–2022 Silverado/Sierra and 2021 GM SUVs with diesel engines: a worn transmission control valve can cause the rear wheels to lock momentarily. Details
- 26V083000 Trucks that may have been repaired incorrectly under 24V797 need the repair redone. Details
NHTSA complaints: 109 keyword-matched complaints for GMC Sierra 1500 2020–2022 (of 1,646 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-15).
Always check your VIN for open recalls at nhtsa.gov/recalls.
Sources
What actually fixed it?
Had this problem? Tell other owners what the real fix was. Reports are counted above; we never show made-up numbers.