You will also need to pull the computer that runs this whole show. It’s usually behind the glovebox liner on the passenger side of the dash. You generally want the one with PN 1227747 and, for our 350 Chevy, the broadcast code (BCC). Unplug the connectors from the computer and you can cut the wires under the dash. You will need to splice in new wires for the check engine light and the ALDL connector. Also grab the ALDL and 6-8 inches of its wires from under the dash near the steering wheel.