Electronic Control Module (ECM): Removal
Turn ignition switch to "OFF" position. Disconnect negative battery cable from battery. Locate ECM and remove access panels, if any. Remove electrical connectors from ECM. Remove ECM from vehicle. Remove PROM and CALPAC (if equipped) from ECM.
CAUTION:
To prevent internal ECM damage, ignition switch must be in "OFF" position when disconnecting or reconnecting power to ECM (for example, battery cable, ECM pigtail, ECM fuse, jumper cables, etc.).