T74 ✓ Factory-verified

Chevrolet · Regular Production Option

Headlamps control, automatic, delay

Years 1963–79, 2001–09, 2014–18, 2022–26 Models 12 Factory citations 56

Query this via API →

Also described as Left hand rule of roadControl, headlamps, automatic, delayHeadlamp control, automatic with delay

Also documented for BuickCadillacGMC

Documented applications

Impala / Full-Size →

• 1963–70s (varies) ◑ Single-source

  This was for exported cars and had to do with the aiming of headlights for LH driving

Avalanche — GMT800 (2002–2006) →

• 2002–2006 ✓ Factory-verified
  ⛭ GM factory document — 2002 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2003 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2004 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2005 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2006 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2002 Chevrolet Avalanche, p.55.

  ⛭ GM Heritage factory kit — 2005 Chevrolet Avalanche, p.34.

Avalanche — GMT900 (2007–2013) →

• 2007–2009 ✓ Factory-verified
  ⛭ GM factory document — 2007 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2008 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM factory document — 2009 chevrolet avalanche 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2007 Chevrolet Avalanche, p.31.

Express — GMT610 (2003–2027) →

• 2014–2018, 2022–2026 ✓ Factory-verified
  ⛭ GM factory document — 2014 chevrolet gh van elec bbm si brief, p.7.

  ⛭ GM factory document — 2015 chevrolet express savana electrical body builders manual service manual 2015 en us, p.16.

  ⛭ GM factory document — 2016 chevrolet express savana electrical body builders manual service manual 2016 en us, p.10.

  ⛭ GM factory document — 2017 chevrolet express savana electrical body builders manual service manual 2017 en us, p.10.

  ⛭ GM factory document — 2018 chevrolet 18 express savana bodybuilders sm 2017nov06, p.16.

  ⛭ GM factory document — 2022 chevrolet 22 express savana electrical body builder sm en us 2021oct12, p.14.

  ⛭ GM factory document — 2023 chevrolet 23 express savana body builder sm en us 2022sep13, p.15.

  ⛭ GM factory document — 2024 chevrolet 24 express savana body builder manual 18553161 2023oct26, p.14.

  ⛭ GM factory document — 2025 chevrolet my25 express savana electrical bbm, p.12.

  ⛭ GM factory document — 2026 chevrolet my26 express savana electrical bbm, p.12.

Silverado — GMT800 (1999–2007) →

• 2001 ✓ Factory-verified
  ⛭ GM factory document — 2001 chevrolet chevy c silverado 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2001 Chevrolet Silverado, p.57.

Silverado — GMT900 (2007–2013) →

• 2009 ✓ Factory-verified

  The 2009 list also prints a Delete entry for this code.

  ⛭ GM factory document — 2009 chevrolet silverado 2wd rpo code list, p.1.

Silverado HD — GMT800 (2001–2007) →

• 2001 ✓ Factory-verified
  ⛭ GM factory document — 2001 chevrolet chevy c silverado 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2001 Chevrolet Silverado HD, p.63.

Silverado HD — GMT900 (2007–2014) →

• 2009 ✓ Factory-verified

  the 2009 list prints it with the delete wording of T78; the reading here is the corpus majority

  ⛭ GM factory document — 2009 chevrolet silverado 2wd rpo code list, p.1.

Suburban — GMT800 (2000–2006) →

• 2001–2006 ✓ Factory-verified
  ⛭ GM factory document — 2001 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2002 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2003 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2004 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2005 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2006 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2001 Chevrolet Suburban, p.52.

  ⛭ GM Heritage factory kit — 2002 Chevrolet Suburban, p.38.

Suburban — GMT900 (2007–2014) →

• 2007–2009, 2014 ✓ Factory-verified

  Trim marks in the 2014 guide: LS, LT, LTZ: S.

  ⛭ GM factory document — 2007 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2008 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2009 chevrolet chevy suburban 2wd rpo code list, p.1.

  ⛭ GM factory document — 2014 chevrolet suburban fleet order guide wayback, p.3.

  ⛭ GM Heritage factory kit — 2007 Chevrolet Suburban, p.35, p.149.

Tahoe — GMT800 (2000–2006) →

• 2001–2006 ✓ Factory-verified
  ⛭ GM factory document — 2001 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2002 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2003 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2004 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2005 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2006 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM Heritage factory kit — 2001 Chevrolet Tahoe, p.45.

  ⛭ GM Heritage factory kit — 2002 Chevrolet Tahoe, p.31.

  ⛭ GM Heritage factory kit — 2003 Chevrolet Tahoe, p.32.

  ⛭ GM Heritage factory kit — 2006 Chevrolet Tahoe, p.29.

Tahoe — GMT900 (2007–2014) →

• 2007–2009, 2014 ✓ Factory-verified

  Trim marks in the 2014 guides: Police: S; Special Service: S.

  ⛭ GM factory document — 2007 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2008 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2009 chevrolet tahoe 2wd rpo code list, p.1.

  ⛭ GM factory document — 2014 chevrolet tahoe police vehicle fleet order guide wayback, p.3.

  ⛭ GM factory document — 2014 chevrolet tahoe special service vehicle fleet order guide wayback, p.3.

  ⛭ GM Heritage factory kit — 2007 Chevrolet Tahoe, p.132, p.191.

Related codes · mentioned in these notes

T78

This page aggregates every documented appearance of T74 in the Chevrolet reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.