Theft deterrent system, fleet immobilizer modifications

Years 2019–20, 2023, 2025–27 Models 3 Factory citations 9

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Also documented for Chevrolet

Documented applications

Savana — GMT610 (2003–2027)

2023 Factory-verified

GM factory document — 2023 chevrolet 23 express savana body builder sm en us 2022sep13, p.12.

Sierra HD — T1XX (2020–2027)

2025–2027 Factory-verified

shortens the roadside key relearn process to three two-minute cycles in place of the standard three ten-minute cycles; Pro, SLE: O; SLT, AT4, AT4X, Denali, Denali Ultimate: not offered

GM factory document — 2025 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2026 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2027 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2025 gmc sierra 2500 hd retail and fleet fleet order guide, p.107.
GM factory document — 2026 gmc sierra 2500 hd retail and fleet fleet order guide, p.103.
GM factory document — 2027 gmc sierra 2500 hd retail and fleet fleet order guide, p.97.

Sierra — T1XX (2019–2026)

2019–2020 Factory-verified

SEO

GM factory document — 2019 gmc 19 sierra 1500 body builder feb 20, p.9.
GM factory document — 2020 gmc 20 sierra 1500 electrical body buil 1, p.9.

This page aggregates every documented appearance of 5L5 in the GMC reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.