How to Install an ECU in a 2003 Buick

by Cecil Fontaine
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All 2003 Buick models use an engine control unit (ECU) to ensure that the vehicle runs properly. The ECU is an on-board computer, located underneath the front passenger floor well. The ECU analyzes signals that are sent from sensors located throughout the vehicle and makes any necessary adjustments. The most common signal of a malfunctioning ECU is the failure of the "Check Engine" light to flash on when starting the vehicle. Keep your car running properly and save money by installing a new model-specific ECU yourself.

Step 1

Raise the hood and disconnect the ground cable from the battery with a socket wrench.

Step 2

Remove the front passenger floor mat and remove the carpeting underneath. Reach into the top of the front passenger floor well and start pulling the carpeting away from the firewall. You will notice that the carpeting is secured with Velcro to a panel on the firewall.

Step 3

Expose the floor well space directly in front of the front passenger seat. You will notice a plastic box in a mounting bracket -- this is the ECU. Use a socket wrench to remove the bolts from the mounting bracket and then remove the bolt that secures a blue plug on the side of the ECU. With these bolts removed, pull the ECU and mounting bracket away from the floor well.

Step 4

Use a screwdriver to remove the screws that keep the ECU in the mounting bracket. Insert the new ECU into the mounting bracket and then reattach the screws to secure it in place.

Step 5

Reinsert the new ECU and mounting bracket into the floor well and then reattach the bolt on the side of the ECU, followed by the mounting bracket bolts. Cover the ECU and mounting bracket with the carpeting -- make sure to secure the carpeting to the firewall again and then reconnect the battery's ground cable.

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