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Frequently Asked Questions

Q: How does the HDGT work?
A: The HDGT reprograms the engine computer (ECM) with engine tuning modifications. Bully Dog’s engine tunes are designed to improve the engine’s efficiency; the result is improved fuel economy and increased horsepower and torque.

Q: How many tunes are available on the HDGT?
A: There are two tunes available: an “economy tune” and an “economy with power tune”.

Q: What does the economy tune do?
A: The economy tune primary purpose is to improve fuel economy without changing a lot of other parameters on the vehicle. Fleet managers are generally choosing this option because they don’t want their drivers to know that anything has changed on the truck, but both owner/operators and fleets are using both tunes with success.

Q: What does the economy with power tune do?
A: The economy with power tune is geared to improving fuel economy while adding extra horsepower for pulling large grades. The economy with power tune adds about a 15% improvement in both horsepower and torque to the rear wheels. Generally, owner operators are using this option.

Q: I’m installing an a Volvo chassis into a Cummins ISX. Do I need a Cummins adapter cable before I do the install?
A: Yes, we highly recommend that if you are installing on a Cummins engine that you have the adapter cable. Volvo is known for having a lot of communication on the bus and that interrupts the installation and sometimes stops it completely. The cable will allow you to bypass the data port connect and plug in directly into the ECM.

Q: Can a customer switch between the economy tune and economy with power tune?
A: Yes, customers can switch between the two tunes as well as return the vehicle to stock. See the product instructions on how to change the tune.

Q: Can a customer load a fuel economy tune on the truck themselves or do they need to use an authorized Bully Dog dealer?
A: If a customer is comfortable with electronics and computers, they are more than free to do the install themselves. We recommend that if you aren’t comfortable that you let one of our trained authorized dealers install one of the fuel economy tunes onto your vehicle.

Q: Where can I purchase the HDGT or HDWD?
A: All Heavy Duty products, including the HDGT and HDWD are available for purchase from any authorized dealer found on our dealer locator.

Q: What do I do if I need to take the vehicle into the dealership for service?
A: Follow these simple steps: 1. Return the vehicle to stock power level using the HDGT 2. Download the program back into the vehicle. Note: If the download is not successful, it means that the dealership put new information on the vehicle that the download does not recognize. Call Bully Dog Technical support for assistance.

Q: How long does the install process take?
A: The install process varies by vehicle make as shown in the chart below. Bully Dog strongly recommends that a minimum of 5 hours is available whenever you download into a truck.

Engine Type Cat® Cummins® EGR Detroit EGR/Cummins DPF Detroit DPF+/Paccar
Read Time 1 min 45 min / 1.5 hrs 5 min 40 min
Download Time 30 min 30 min / 1 hr 5 min 5 min

Q: What do I do if the HDGT freezes during the engine read process?
A: Follow these simple steps: 1. Turn the key to the off position and unplug the HDGT from the data port. 2. Try to resume the read where it left off, try up to 3 more times.

Note: if the vehicle has an automatic transmission, pull the transmission fuse and try again. If pulling the transmission fuse works then leave the fuse out until the entire download process is complete. Other fuses might need to be pulled, like ABS fuses if the HDGT continues to freeze.

Q: What do I do if the HDGT or HDWD does not light up when I plug it into the data port?
A: Check your data port fuses or any associated fuses and replace them as needed. Ensure that the key is on because sometimes the data port is tied to a key-on fuse.

Q: What do I do when the download is complete?
A: Test the product our by taking a nice long drive and then send us a testimonial please!


Q: Does Bully Dog offer a money back guarantee on its Heavy Duty Products?
A: Yes, the Bully Dog offers a 30 day money back guarantee on all of its products including the HDGT.

Q. Does Bully Dog offer a warranty on the product?
A: Yes, all electronic products from Bully Dog are covered by a 1 year warranty policy. Turbos have a 1 year/100,000 mileage warranty and the ceramic coated exhaust manifolds have a 2 year warranty.

Q. Are the tunes safe to install onto the tractor?
A. Yes, Bully Dog engineers have worked to ensure that the programs do not exceed safety parameters. We suggest using caution if you have already tuned the truck to the highest horsepower level or have the highest OEM horsepower tune for your configuration. Transmissions, clutches and drive lines already set to their highest horsepower level should not be exceeded.

Q. How long has Bully Dog had Heavy Duty product out in the field in real everyday use?
A. The Bully Dog Big Rig downloaders were officially released in March of 2008, but product has been in research and development since 2006. Bully Dog has been tuning engines since 1998.