Control Module Disconnection

Wait 3 minutes after turning off the ignition before unplugging the connectors from the engine control module (ECM). The system relay must have released the voltage before the control module is removed from the vehicle. If the engine cooling fan runs after the ignition has been turned off, wait until it has stopped. Then wait an additional 3 minutes.
Release the engine control module (ECM) as per:
see PLENUM CHAMBER