Download How to Install Turbocharger System on ‘06 Hummer H3 – 1. Turn the ignition switch to the OFF position & disconnect the battery. 2. Locate the ECU, located in the engine bay. It is on the passenger side of the firewall, behind the windshield washer and coolant fluid reservoirs. It is not necessary to remove the fluid reservoirs in order to access the ECU. SEE FIGURE 1. 3. Lift up the plastic safety locks on the ECU plugs in order to remove them. SEE FIGURE 2 & FIGURE 3. 4. Carefully unplug the wiring harness from the ECU by lifting up the plug locks. SEE FIGURE 4. 5. Unclip the ECU from its plastic frame and slide it out of place. SEE FIGURE 5 & FIGURE 6. 6. Once removed from the car, attach the Serial No. decal (P/N 31039) to the backside of the ECU. Fill out the information on the label with a permanent black pen or thin-tip marker. 7. Package your ECU in the return box (P/N 31009), using the supplied foam packaging inserts (P/N 31011). Fill in your address on the Fedex return label (P/N 31038), and apply it to the outside of the box. Seal the box closed with the supplied Electronic Mat’l decal (P/N 31043).