How to Reprogram My Truck to Improve My Gas Mileage

by Francis Walsh

Your truck is partially controlled by a computer because computers make an engine run reliably, but most lack good performance or excellent fuel economy. After-market programs produce better gas mileage and performance simply by uploading a new computer program into a truck's ECU (electronic control unit). If you are thinking "I want to know how to reprogram my truck to improve my gas mileage," this article explains how. You can even store your existing program for later use if you want.

Park the truck in a well lit area. Locate the DLC (data link connector) for your truck, which will be located just under the bottom edge of the dashboard to the left of the steering column. Uncover the plug to expose the adapter and its connector.

Insert the data transfer cord from a programmer like the kind from HYPERTECH® ( into the DLC (data link connector). Turn the ignition key to the "on" position without starting the truck. ONSTAR® equipped vehicles will need to disconnect the service at the fuse box to prevent interruptions in the data transfer once it begins. Trucks equipped with daytime lights will need to have the emergency brake engaged to turn those off while the new program is being uploaded.

Follow the step-by-step instruction as directed by the hand-held programmer of choice. Answer each question as it is displayed through the process of downloading the factory settings and uploading the new fuel saving program directly into the ECU (electronic control unit) of your truck.

Disconnect the data transfer cable connecting the programmer to the truck via the DLC (data link connector). Cover the plug with the cap. Turn the ignition key all the way back before starting the truck. Disengage the parking brake, reconnect ONSTAR®, and then start the truck. Troubleshoot any problems per the manufacturer's recommendations and drive normally to see the new fuel savings. When you first asked "How do I reprogram my truck to improve my gas mileage?" you never thought it would be so easy.


  • check Install a high temperature thermostat (180 degrees). Check the pressure in your tires weekly. Do not drive over the posted speed limits and avoid rapid acceleration or coming to quick stops. Do not idle for longer than ninety seconds. "You waste more gas idling than you do restarting the truck after that long."


  • close The uploading and downloading of programs into and from your truck's computer can be interrupted, possibly creating a glitch in the operation once it has completed downloading or uploading. Disconnecting remote services like ONSTAR® and turning off daytime headlights may be the key to getting the new programs on and off the computer without error.

Items you will need

About the Author

Francis Walsh has been working as a freelance writer since 2003. He has contributed to websites such as Shave, Autogeek and Torque & Chromeas, as well as provided content for private clients. Walsh has worked as a performance part-packer and classic car show promoter, now serving as crew chief for Nitrousfitz Racing.

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Photo Credits

  • photo_camera detail: glowing dashboard image by davidcrehner from