2019-2021 GMC Sierra 1500 Auto Start Stop Eliminator | Plug & Play

A plug-and-play memory harness for the 2019–2021 GMC Sierra 1500. Out of the factory, Auto Stop/Start comes back on at every key cycle. This module remembers your last choice and sends it again at the next start. It plugs in line with the factory connector named in the instructions, using factory-style plugs on both ends, so nothing is cut or spliced.

You can still use the original button at any time. Whatever you select last is what the module repeats on the next start. Take the module out and the vehicle behaves exactly as it did from the factory.

Covered model years

Listed applications (each row is a 100% fitment match for the factory connector this part uses):

• GMC Sierra 1500: 2019–2021

For reference, the GMC Sierra 1500 in these years is a full-size pickup offered with 2.7L turbo four-cylinder, 4.3L V6, 5.3L V8, 6.2L V8 and 3.0L Duramax turbo-diesel engines. Trim levels are not split out in the table, so confirm that your vehicle has the stop-start button before ordering.

How factory stop-start works on the GMC Sierra 1500

On the GMC Sierra 1500, Auto Stop/Start shuts the engine down at a stop and fires it back up as the brake is released. You can switch it off with the dash button, but the choice is not saved. The next ignition cycle brings the default back. The module keeps the choice you made instead.

What to expect

• Holds the stop-start button state between drives.
• Lets you re-enable the system with the factory button at any time.
• Leaves no permanent change after removal.
• Leaves engine and transmission software untouched.

Typical reasons to keep it off

Drivers usually switch stop-start off for comfort or habit. A restart at every stop is noticeable in a full-size pickup, the climate system may run at reduced output while the engine is off, and quick moves into traffic feel slower when the engine has to fire first. If those are your reasons, you probably press the button on every drive now. With the module, you press it once.

Battery and charging

If the stop-start indicator shows the system as unavailable, test the battery before anything else. On stop-start vehicles that is the most common cause. A replacement should match the original specification (AGM or EFB), and some manufacturers call for a battery monitor reset after the swap.

Conditions the factory system checks

Auto stop needs several conditions at once: a warm engine, enough battery charge, moderate cabin heating or cooling demand, and the vehicle fully stopped with the brake held. If any is missing, the engine keeps running. The module only remembers the button state; the factory controller still decides whether a stop is allowed.

Where it connects

It plugs in line with the factory connector named in the instructions, using factory-style plugs on both ends, so nothing is cut or spliced. Work with the ignition off. Seat each connector until its lock engages, then secure the module with the supplied ties or tape so it cannot rattle or touch pedals, steering parts or anything hot. Start the vehicle, press the stop-start button once, then restart to confirm the choice is held.

Before blaming the module

A warning light that appears after installation usually means a connector is not fully seated. Switch the ignition off, reseat both ends until the locks click, and test again. If the light stays on, remove the module and confirm the vehicle is fault-free on its own before contacting support.

Fitment check

• Model year and model match a row in the table above (2019–2021 GMC Sierra 1500).
• Your GMC Sierra 1500 has the factory stop-start button. Base trims or engines without stop-start have nothing for the module to remember.
• The battery and charging system test good and no warning lights are on.
• The connector at your install point matches the one in the product photos.
• No aftermarket remote start, alarm or gateway bypass is wired into the same circuit. If one is, email support before ordering.
• If you are unsure, send your VIN to support@automotivebypass.com and we will confirm fitment.

Shipping, returns and warranty

Standard shipping inside the lower 48 states costs nothing; allow 1–2 business days of handling plus 3–4 in transit. Returns need approval first and must be requested within 45 days. Approved returns are subject to a 20% restocking fee, with return shipping paid by the customer. A 3-year limited warranty applies. Email support@automotivebypass.com (Mon–Fri, 9–5 PST) with your VIN if you want a fitment check.