If the battery is disconnected, several systems must be re-teamed before they will work properly. The Powertrain Control Module (PCM) cannot be replaced at home because the new unit must be reprogrammed with a proprietary scan tool. The PCM in many models is housed inside a special metal anti-theft box, making it extremely difficult to remove. Begin by disconnecting the cable from the negative battery terminal, then remove the cover from the electronics box. If necessary, take out the air filter housing, release the tabs, and remove the PCM cover if equipped. Pull back the tabs with your fingers and lift the PCM up and out of the bracket while keeping the connector connected, positioning it to the side. For models without anti-theft equipment, slide the connector retainers out and pull the connectors from the PCM, ensuring to release the connector locks. On models with anti-theft equipment, if the PCM only needs to be moved to the side for servicing of other components, stop at this point. The installation process is the reverse of removal. For models equipped with an anti-theft housing or cover plate, perform the initial steps to release the PCM from the bracket. The anti-theft equipment is secured with shear-head bolts; cut slots in these bolts using a small cutting wheel or grinder, then unscrew them with a flat blade screwdriver, or alternatively, drill through the bolts and use a screw extractor. Disconnect the electrical connectors and remove the PCM, with installation following the reverse of the removal procedure.