Recipe - Duramax 6.6L V8 Turbo Diesel (GM HD, LML 2011-2016; LGH vans 2011-2016)
Specific Fix build
Reliability tier: verified - verify before ordering, see /disclosure/
Cold-start repair for the LML (mode Glow plug / control module cold-start service (LML)): glow plugs fail open with age and the control module's drivers fail with or without plug faults. Test per-cylinder resistance before replacing plugs; a failed module often kills a bank, not one plug. The module splits at 2012/2013 - confirm the window.
Parts
- Duramax LML Glow Plug (OEM) - glow plug, one per cylinder (12639701) (qty 8)
- Duramax LML Glow Plug Control Module 2011-2012 (OEM) - control module, 2011-2012 (12652113) (qty 1)
- Duramax LML Glow Plug Control Module 2013-2016 (OEM) - control module, 2013-2016 (12650593) (qty 1)
- Duramax LML Intake Air Heater (OEM) - intake grid air heater when cold starts stay rough after plugs/module (12697819) (qty 1)
Install order
- measure glow-plug resistance per cylinder; map which bank is down
- module (window split 2011-2012 / 2013-2016) when a bank or the whole circuit is dead
- renew failed plugs; minimize extended cranking - hard cranking on a weak fuel system compounds the complaint
- intake air heater check for lingering cold roughness
Expected outcome
Clean cold starts, no glow-circuit codes.
Do not
- do not replace plugs one at a time across years - map the circuit first
Parts budget
About $170-$280 in parts. It depends on what the diagnosis finds; each option below is what you buy together. Prices marked "at Dave's" are Dave's Auto Center's, the same as in his store; the others are approximate prices from OEM and maker catalogs, rounded (a manufacturer's list price can run higher). Parts only, no labor.